141 results on '"Masashige Matsumoto"'
Search Results
2. Electric Dipole Active Magnetic Resonance and Nonreciprocal Directional Dichroism in Magnetoelectric Multiferroic Materials in Terahertz and Millimeter Wave Regions
- Author
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Noriki Terada, Hidekazu Tanaka, Masayuki Hagiwara, Masashige Matsumoto, and Shojiro Kimura
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Physics ,Condensed matter physics ,Magnetic dipole transition ,Physics::Optics ,010402 general chemistry ,Coupling (probability) ,01 natural sciences ,Electromagnetic radiation ,Atomic and Molecular Physics, and Optics ,030218 nuclear medicine & medical imaging ,0104 chemical sciences ,Condensed Matter::Materials Science ,03 medical and health sciences ,Dipole ,Polarization density ,0302 clinical medicine ,Electric field ,Condensed Matter::Strongly Correlated Electrons ,Spin (physics) ,Excitation - Abstract
We review electric dipole active magnetic resonance and nonreciprocal directional dichroism in magnetoelectric multiferroic materials in terahertz and millimeter wave regions. Owing to dynamical magnetoelectric coupling generated by the spin-dependent electric polarization, magnetic resonance, which usually occurs owing to magnetic dipole transition, can be induced by the oscillating electric fields of electromagnetic wave. This electric dipole active magnetic resonance can be useful for microscopic investigations of magnetic excitation in unconventional spin systems. The magnetoelectric coupling also induces the nonreciprocal directional dichroism, which provides a novel functionality to materials as an optical diode, in teraheltz and microwave absorption by magnetic resonance. As examples, we describe the results of the high field ESR measurements of the triangular lattice antiferromagnet $$\hbox {CuFeO}_{\mathrm{2}}$$ and the interacting quantum spin dimer systems $$\hbox {TlCuCl}_{\mathrm{3}}$$ and $$\hbox {KCuCl}_{\mathrm{3}}$$ .
- Published
- 2021
3. First ESR Detection of Higgs Amplitude Mode and Analysis with Extended Spin-Wave Theory in Dimer System KCuCl$$_3$$
- Author
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Hidekazu Tanaka, Hitoshi Ohta, Yoshiya Uwatoko, Takahiro Sakurai, Yuki Hirao, and Masashige Matsumoto
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Quantum phase transition ,High Energy Physics::Lattice ,FOS: Physical sciences ,010402 general chemistry ,01 natural sciences ,030218 nuclear medicine & medical imaging ,Condensed Matter - Strongly Correlated Electrons ,03 medical and health sciences ,0302 clinical medicine ,Spin wave ,Quantum critical point ,Spin-½ ,Physics ,Condensed Matter - Materials Science ,Strongly Correlated Electrons (cond-mat.str-el) ,Condensed matter physics ,High Energy Physics::Phenomenology ,Materials Science (cond-mat.mtrl-sci) ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Condensed Matter - Other Condensed Matter ,Dipole ,Amplitude ,Higgs boson ,Condensed Matter::Strongly Correlated Electrons ,Excitation ,Other Condensed Matter (cond-mat.other) - Abstract
KCuCl$_3$ is known to show a quantum phase transition from the disordered to antiferromagnetically ordered phases by applying pressure. There is a longitudinal excitation mode (Higgs amplitude mode) in the vicinity of the quantum critical point in the ordered phase. To detect the Higgs amplitude mode, high-pressure ESR measurements are performed in KCuCl$_3$. The experimental data are analyzed by the extended spin-wave theory on the basis of the vector spin chirality. We report the first ESR detection of the Higgs amplitude mode and the important role of the electric dipole described by the vector spin chirality., 24 pages, 12 figures
- Published
- 2020
4. Study of spin-isospin responses of radioactive nuclei with the background-reduced neutron spectrometer, PANDORA
- Author
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N. Fukuda, Takashi Nakamura, H. Sakai, Yohei Shimizu, J. Gibelin, Makoto Yasuda, Tomotsugu Wakasa, M. Nishimura, J. Gao, Masashige Matsumoto, S. Franchoo, H. Miki, H. Kasahara, T. Harada, Masaki Sasano, D. Tudor, Toshio Kobayashi, T. Isobe, G. G. Kiss, Tomohiro Uesaka, Yasuhiro Togano, Susumu Shimoura, Atsumi Saito, N. Zhang, I. C. Stefanescu, E. Takada, Zoltán Halász, L. Trache, Yuya Kubota, D. Kim, T. Shimada, Shoko Koyama, Y. Fujino, Juzo Zenihiro, Z. Korkulu, D. Inomoto, Zaihong Yang, H. Sato, H. N. Liu, A. Spiridon, M. Miwa, H. Suzuki, L. Stuhl, V. Panin, H. Baba, Yosuke Kondo, S. Park, K. Yoneda, T. Motobayashi, Y. L. Sun, T. Tomai, I. S. Hahn, Kentaro Yako, X. Sun, A. Kurihara, M.N. Harakeh, Y. Hirai, D. S. Ahn, A. I. Chilug, Hideaki Otsu, Hiroki Yamada, Shin'ichiro Michimasa, K. Yoshida, Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Research unit Nuclear & Hadron Physics, Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), and Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)
- Subjects
Nuclear and High Energy Physics ,Nuclear Theory ,n) reactions ,Inverse-kinematics (p, n) reactions ,01 natural sciences ,Low-energy neutron detector ,Inverse-kinematics [formula omitted] reactions ,Nuclear physics ,0103 physical sciences ,Figure-of-Merit (FoM) ,Neutron detection ,Neutron ,010306 general physics ,Spin (physics) ,Nuclear Experiment ,Instrumentation ,Gamow-Teller transition ,DETECTOR ,Real-time pulse-shape discrimination ,Physics ,[PHYS]Physics [physics] ,Spin-isospin response ,Spectrometer ,010308 nuclear & particles physics ,Figure-of-Merit (RIM) ,Detector ,PULSE-SHAPE DISCRIMINATION ,PLASTIC SCINTILLATOR ,Inverse-kinematics (p ,Isospin ,Ground state ,Beam (structure) - Abstract
The status of a project to measure spin-isospin responses of neutron drip-line nuclei using a new low-energy neutron detector, PANDORA (Particle Analyzer Neutron Detector Of Real-time Acquisition), is reported. The performance of PANDORA was characterized by the 6He(p,n)6Li reaction in inverse kinematics at the HIMAC facility in Chiba. Observation of the strong transition to the ground state in 6Li is discussed. Preliminary results of 11Li(p,n)11Be and 14Be(p,n)14B experiments in inverse kinematics at RI Beam Factory (RIBF) of RIKEN Nishina Center are also presented including the exotic decay channel of 11Be→9Li + d. Details of the experimental setup based on PANDORA and the SAMURAI large-acceptance magnetic spectrometer, as well as the combined data-acquisition system are described. The neutron-gamma discrimination capability of PANDORA was evaluated, Figure-of-Merit (FoM) values higher than those found in the literature for similar materials were derived from experimental data.
- Published
- 2020
5. Magnetoacoustic Resonance to Probe Quadrupole-Strain Coupling in a Diamond Nitrogen-Vacancy Center as a Spin-Triplet System
- Author
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Mikito Koga and Masashige Matsumoto
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Physics ,Coupling ,Condensed Matter - Materials Science ,Strain (chemistry) ,Strongly Correlated Electrons (cond-mat.str-el) ,Condensed Matter - Mesoscale and Nanoscale Physics ,General Physics and Astronomy ,Resonance ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,Measure (mathematics) ,Condensed Matter::Materials Science ,Condensed Matter - Strongly Correlated Electrons ,Quadrupole ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Molecular symmetry ,Condensed Matter::Strongly Correlated Electrons ,Atomic physics ,Spin (physics) ,Nitrogen-vacancy center - Abstract
A theory of magnetoacoustic resonance is proposed to measure quadrupole-strain couplings in a spin-triplet state with the $C_{3v}$ point group symmetry, considering the spin-strain interaction in a diamond nitrogen-vacancy (NV) center. Based on the Floquet theory, we demonstrate how the single- and two-phonon transition probabilities depend on the change in the longitudinal and transverse quadrupole couplings, which can be controlled by rotating an applied magnetic field, around the threefold axis. The obtained quadrupole dynamics results are useful for realizing mechanical or ac strain-control of the NV spin as an alternative to the conventional magnetic control by spin resonance., 13 pages, 5 figures
- Published
- 2020
6. Spin-driven ferroelectricity in the quantum magnet TlCuCl3 under high pressure
- Author
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Hidekazu Tanaka, Kyosuke Sakurai, Staoshi Awaji, Masashige Matsumoto, and Shojiro Kimura
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Condensed Matter::Quantum Gases ,Physics ,Condensed matter physics ,Condensed Matter::Other ,Magnon ,02 engineering and technology ,Dielectric ,021001 nanoscience & nanotechnology ,01 natural sciences ,Ferroelectricity ,Landau theory ,Condensed Matter::Materials Science ,Polarization density ,0103 physical sciences ,Condensed Matter::Strongly Correlated Electrons ,010306 general physics ,0210 nano-technology ,Spin (physics) ,Quantum ,Quantum fluctuation - Abstract
In this study, dielectric constant and pyroelectric current measurements under high pressure up to 16.7 kbar have been performed for the interacting spin dimer system ${\mathrm{TlCuCl}}_{3}$, which exhibits spin-driven ferroelectricity in the magnon Bose-Einstein condensation (BEC) phase with strong quantum spin fluctuation. When pressure is applied, the magnon BEC phase becomes significantly stabilized, whereas the value of the electric polarization decreases in high-pressure regions. It is also observed that electric polarization becomes harder under pressure. Analyses based on both a Landau theory and a microscopic spin Hamiltonian demonstrate that the suppression of quantum fluctuation on the application of pressure caused the observed pressure effects. Consequently, it is revealed that the ferroelectricity in ${\mathrm{TlCuCl}}_{3}$ is highly governed by the quantum spin fluctuation.
- Published
- 2020
7. Electrical Switching of the Nonreciprocal Directional Microwave Response in a Triplon Bose-Einstein Condensate
- Author
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Masashige Matsumoto, Hidekazu Tanaka, and Shojiro Kimura
- Subjects
Condensed Matter::Quantum Gases ,Physics ,Condensed matter physics ,General Physics and Astronomy ,01 natural sciences ,Ferroelectricity ,law.invention ,Polarization density ,law ,Electric field ,0103 physical sciences ,Quasiparticle ,Antiferromagnetism ,Condensed Matter::Strongly Correlated Electrons ,010306 general physics ,Spin (physics) ,Bose–Einstein condensate ,Microwave - Abstract
We present a microwave electron spin resonance study of the quantum spin dimer system TlCuCl_{3}, which shows the magnetic-field-induced ordering with both antiferromagnetic spin order and ferroelectricity by the Bose-Einstein condensation (BEC) of triplon quasiparticles. Our main achievement is an electrical switching of the nonreciprocal directional microwave response in the triplon BEC phase. High-speed directional control of microwave absorption by applying an electric field has been accomplished in this Letter. The strength of the observed nonreciprocal microwave response well agrees with the calculation based on Kubo theory with the parameters, evaluated from the static electric polarization in this material.
- Published
- 2020
8. Spin and charge controlled by antisymmetric spin-orbit coupling in a triangular-triple-quantum-dot Kondo system
- Author
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Hiroaki Kusunose, Mikito Koga, and Masashige Matsumoto
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Physics ,Condensed matter physics ,Kondo insulator ,02 engineering and technology ,Spin–orbit interaction ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Electronic, Optical and Magnetic Materials ,Magnetic field ,Polarization density ,Quantum mechanics ,Quantum critical point ,0103 physical sciences ,Kondo effect ,Electrical and Electronic Engineering ,010306 general physics ,0210 nano-technology ,Ground state ,Spin (physics) - Abstract
We study a local antisymmetric spin-orbit (ASO) coupling effect on a triangular-triple-quantum-dot (TTQD) system as a theoretical proposal for a new application of the Kondo physics to nanoscale devices. The electric polarization induced by the Kondo effect is strongly correlated with the spin configurations and molecular orbital degrees of freedom in the TTQD. In particular, an abrupt sign reversal of the emergent electric polarization is associated with a quantum critical point in a magnetic field, which can also be controlled by the ASO coupling that changes the mixing weight of different orbital components in the TTQD ground state.
- Published
- 2018
9. Higgs amplitude mode in a two-dimensional quantum antiferromagnet near the quantum critical point
- Author
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K. Coester, Bastian Klemke, Sachith Dissanayake, Kai Phillip Schmidt, Mark M. Turnbull, Yiming Qiu, H. Agrawal, Wangchun Chen, Tao Hong, Thomas R. Gentile, Shannon Watson, Firas F. Awwadi, Rasmus Toft-Petersen, David Tennant, and Masashige Matsumoto
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Physics ,Quantum phase transition ,High Energy Physics::Phenomenology ,General Physics and Astronomy ,02 engineering and technology ,Neutron scattering ,021001 nanoscience & nanotechnology ,01 natural sciences ,Higgs field ,Amplitude ,Quantum mechanics ,Quantum critical point ,Quantum electrodynamics ,0103 physical sciences ,Higgs boson ,Quasiparticle ,010306 general physics ,0210 nano-technology ,Quantum - Abstract
The presence of a Higgs amplitude mode is revealed in a two-dimensional spin-half quantum antiferromagnet, C9H18N2CuBr4 by means of neutron scattering. Spontaneous symmetry-breaking quantum phase transitions play an essential role in condensed-matter physics1,2,3. The collective excitations in the broken-symmetry phase near the quantum critical point can be characterized by fluctuations of phase and amplitude of the order parameter. The phase oscillations correspond to the massless Nambu–Goldstone modes whereas the massive amplitude mode, analogous to the Higgs boson in particle physics4,5, is prone to decay into a pair of low-energy Nambu–Goldstone modes in low dimensions2,6,7. Especially, observation of a Higgs amplitude mode in two dimensions is an outstanding experimental challenge. Here, using inelastic neutron scattering and applying the bond-operator theory, we directly and unambiguously identify the Higgs amplitude mode in a two-dimensional S = 1/2 quantum antiferromagnet C9H18N2CuBr4 near a quantum critical point in two dimensions. Owing to an anisotropic energy gap, it kinematically prevents such decay and the Higgs amplitude mode acquires an infinite lifetime.
- Published
- 2017
10. Symmetry Analysis of Magnetoelectric Effects in Honeycomb Antiferromagnet Co4Nb2O9
- Author
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Mikito Koga and Masashige Matsumoto
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Physics ,Condensed Matter - Materials Science ,Condensed matter physics ,Strongly Correlated Electrons (cond-mat.str-el) ,General Physics and Astronomy ,Space group ,Honeycomb (geometry) ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,Crystal structure ,Symmetry group ,Coupling (probability) ,01 natural sciences ,Symmetry (physics) ,010305 fluids & plasmas ,Ion ,Condensed Matter::Materials Science ,Condensed Matter - Strongly Correlated Electrons ,Physics::Plasma Physics ,0103 physical sciences ,Antiferromagnetism ,Condensed Matter::Strongly Correlated Electrons ,Astrophysics::Earth and Planetary Astrophysics ,010306 general physics ,Physics::Atmospheric and Oceanic Physics - Abstract
Magnetoelectric effects in honeycomb antiferromagnet Co4Nb2O9 are investigated on the basis of symmetry analyses of Co ions in trigonal P-3c1 space group. For each Co ion, the possible spin dependence is classified by C3 point-group symmetry. This accounts for the observed main effect that an electric polarization rotates in the opposite direction at the twice speed relative to the rotation of the external magnetic field applied in the ab-plane. Inversion centers and twofold axes in the unit cell restrict the active spin-dependence of the electric polarization, which well explains the observed experimental results. Expected optical properties of quadrupolar excitation and various types of dichroism are also discussed., Comment: 15 pages, 12 figures
- Published
- 2019
- Full Text
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11. Total Moment Sum Rule for Magnets in the Vicinity of Quantum Critical Point
- Author
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Masashige Matsumoto
- Subjects
Physics ,Condensed Matter - Materials Science ,Strongly Correlated Electrons (cond-mat.str-el) ,Phase (waves) ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,General Physics and Astronomy ,Moment (mathematics) ,Condensed Matter - Strongly Correlated Electrons ,Transverse plane ,Quantum mechanics ,Magnet ,Quantum critical point ,Condensed Matter::Strongly Correlated Electrons ,Sum rule in quantum mechanics ,Quantum ,Excitation - Abstract
It is known that the longitudinal and transverse excitation modes can exist in the vicinity of a quantum critical point in the ordered phase of quantum magnetic systems. The total moment sum rule for such systems is derived on the basis of the extended spin-wave theory, where both longitudinal and transverse magnetic excitations are taken into account. The sum rule is resolved into elastic, one-magnon, and two-magnon components. The formulation is applicable to spin systems with the longitudinal mode, such as $S=1$ systems with single-ion anisotropy of easy-plane type and spin dimer systems. The result helps us analyze and understand measured data of inelastic neutron scattering., Comment: 16 pages, 10 figures
- Published
- 2021
12. Study of spin-isospin response of 11Li neutron-drip-line nucleus with PANDORA
- Author
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Masaki Sasano, M. Miwa, T. Kobayashi, I. C. Stefanescu, D. Tudor, Tomohiro Uesaka, T. Isobe, K. Yoneda, D. Inomoto, Zaihong Yang, M. Nishimura, L. Stuhl, H. Baba, I. S. Hahn, D. Kim, K. Yoshida, A. I. Chilug, Y. Fujino, H. Suzuki, H. Sato, Yosuke Kondo, Zoltán Halász, H. Kasahara, Kentaro Yako, Tomotsugu Wakasa, Yasuhiro Togano, G. G. Kiss, T. Motobayashi, T. Shimada, Shin'ichiro Michimasa, X. Sun, Naoki Fukuda, Juzo Zenihiro, H. N. Liu, Takashi Nakamura, S. Park, Masashige Matsumoto, H. Miki, Y. Hirai, V. Panin, Hiroki Yamada, A. Spiridon, T. Tomai, Susumu Shimoura, Y. L. Sun, D. S. Ahn, M. N. Harakeh, H. Sakai, Makoto Yasuda, A. Kurihara, Atsumi Saito, N. Zhang, L. Trache, Yuya Kubota, J. Gibelin, Yohei Shimizu, S. Franchoo, Hideaki Otsu, J. Gao, Shoko Koyama, Z. Korkulu, T. Harada, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)
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Physics ,History ,010308 nuclear & particles physics ,Nuclear Theory ,[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex] ,01 natural sciences ,Computer Science Applications ,Education ,Nuclear physics ,medicine.anatomical_structure ,Isospin ,0103 physical sciences ,medicine ,Nuclear drip line ,Nuclear Experiment ,010306 general physics ,Nucleus ,Spin-½ - Abstract
The spin-isospin responses of the 11Li drip-line nucleus has been measured. Preliminary results of the 11Li(p, n)11Be experiment in inverse kinematics at RI Beam Factory (RIBF) of RIKEN Nishina Center are presented including the observation of 1n, 2n, t, d, 2α and 6He+α decay channels of 11Be reaction product. Details of the experimental setup based on PANDORA (Particle Analyzer Neutron Detector Of Real-time Acquisition) low-energy neutron detector and the SAMURAI large-acceptance magnetic spectrometer are described.
- Published
- 2020
13. Analysis of Magnetoacoustic Quadrupole Resonance and Application to Probe Quadrupole Degrees of Freedom in Quantum Magnets
- Author
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Mikito Koga and Masashige Matsumoto
- Subjects
Physics ,Condensed Matter - Materials Science ,Strongly Correlated Electrons (cond-mat.str-el) ,Degrees of freedom ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,General Physics and Astronomy ,Resonance ,Condensed Matter - Strongly Correlated Electrons ,Magnet ,Quadrupole ,Ultrasonic sensor ,Atomic physics ,Quantum - Abstract
Motivated by the recent progress of high-frequency ultrasonic measurements, we propose a theory of magnetoacoustic resonance as a microscopic probe for quadrupole degrees of freedom hidden in magnetic materials. A local strain driven by an acoustic wave couples to electronic states of a magnetic ion through various quadrupole-strain couplings, and this provides a periodically time-dependent oscillating field. As a typical two-level system with the quadrupole, we consider a non-Kramers doublet and investigate single- and multiphonon-mediated transition processes on the basis of the Floquet theory. An analytic form of the transition probability is derived within the weak coupling theory, which helps us analyze the magnetoacoustic quadrupole resonance. We apply the theory to realistic non-Kramers doublet systems for the f2 configuration in Oh and D4h symmetries, and discuss how to identify the relevant quadrupole by controlling the quadrupole-strain coupling with an applied magnetic field in ultrasonic measurements., 13 pages, 5 figures
- Published
- 2020
14. Analysis of Field-Induced Nonreciprocal Magnon in Noncollinear Magnet and Application to S = 1 Triangular Antiferromagnet CsFeCl3
- Author
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Shohei Hayashida, Takatsugu Masuda, and Masashige Matsumoto
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Physics ,Condensed matter physics ,Field (physics) ,Magnon ,Physics::Optics ,General Physics and Astronomy ,01 natural sciences ,Symmetry (physics) ,010305 fluids & plasmas ,Condensed Matter::Materials Science ,Similarity (network science) ,Magnet ,Dispersion relation ,0103 physical sciences ,Antiferromagnetism ,010306 general physics - Abstract
Magnetic field-induced nonreciprocal magnon in noncollinear magnet is investigated in detail from symmetry viewpoint. To understand the nonreciprocal dispersion relation, we discuss similarity to t...
- Published
- 2020
15. Theory of Photon-Assisted Magnetoacoustic Resonance as a New Probe of Quadrupole Dynamics
- Author
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Masashige Matsumoto and Mikito Koga
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Physics ,Floquet theory ,Condensed Matter - Materials Science ,Photon ,Strongly Correlated Electrons (cond-mat.str-el) ,Condensed matter physics ,Phonon ,Surface acoustic wave ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,General Physics and Astronomy ,Resonance ,law.invention ,Magnetic field ,Condensed Matter - Strongly Correlated Electrons ,law ,Quadrupole ,Electron paramagnetic resonance - Abstract
Motivated by the recent progress of phonon-mediated control in quantum spin devices, we propose a possibility of hybrid measurement using electron paramagnetic resonance (EPR) and a surface acoustic wave (SAW). Considering quadrupole-strain (QS) couplings suggested for silicon vacancies, we present a minimum model of the two-level system to investigate a magnetoacoustic resonance (MAR) coupled to various strain modes driven by the SAW. The longitudinal and transverse QS couplings can be changed by rotating a magnetic field, which depends on a combination of the strain modes. Using the Floquet theory, we elucidate each coupling effect on the time-averaged transition probability, especially focus on a single-phonon transition process. The important result is that the longitudinal QS coupling brings about a sharp photon-assisted resonance and leads to an abrupt change in the field-angle dependent transition probability. Since this phonon transition process is always accompanied by the photon transition, the field angle for the sharp resonance peak can be detected by the EPR measurement. The hybrid EPR-MAR measurement is useful to confirm the existence of quadrupole degrees of freedom strongly coupled to elastic strains, and thus it is expected to be a complementary probe for the precise evaluation of quadrupole properties., Comment: 10 pages, 12 figures
- Published
- 2020
16. Erratum: Magnetism of the antiferromagnetic spin- 32 dimer compound CrVMoO7 having an antiferromagnetically ordered state [Phys. Rev. B 95 , 144429 (2017)]
- Author
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James R. Hester, Taku J. Sato, Masashi Hase, Masashige Matsumoto, Akira Matsuo, Haruhiko Kuroe, Hiroki Yamazaki, Koichi Kindo, and Yuta Ebukuro
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Physics ,Condensed matter physics ,Magnetism ,Dimer ,02 engineering and technology ,State (functional analysis) ,021001 nanoscience & nanotechnology ,01 natural sciences ,chemistry.chemical_compound ,chemistry ,0103 physical sciences ,Antiferromagnetism ,010306 general physics ,0210 nano-technology ,Spin (physics) - Published
- 2018
17. Polarization analysis of magnetic excitation in multiferroic Ba2CoGe2O7
- Author
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Bertrand Roessli, Takatsugu Masuda, Hazuki Kawano-Furukawa, Minoru Soda, Jonathan S. White, Lieh-Jeng Chang, V. Ovidiu Garlea, and Masashige Matsumoto
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Physics ,Condensed matter physics ,Neutron spectra ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Polarization (waves) ,01 natural sciences ,Longitudinal mode ,0103 physical sciences ,Neutron ,Multiferroics ,010306 general physics ,0210 nano-technology ,Anisotropy ,Excitation - Abstract
Magnetic excitations in the multiferroic ${\mathrm{Ba}}_{2}{\mathrm{CoGe}}_{2}{\mathrm{O}}_{7}$ are measured by combination of unpolarized and polarized neutron-scattering techniques. The unpolarized neutron spectrum reveals an anisotropic $\mathbf{Q}$ dependence of the intensity of the electromagnon mode at 4 meV. The analysis of the polarized neutron spectra identifies the directions of the magnetic fluctuations of the observed modes. The determined modes are consistent with the calculation by the extended spin-wave theory. A couple of transverse modes and a single longitudinal mode are involved in the magnetic excitation of ${\mathrm{Ba}}_{2}{\mathrm{CoGe}}_{2}{\mathrm{O}}_{7}$. The longitudinal fluctuation takes on a main role in the electromagnon mode.
- Published
- 2018
18. Electric dipole spin resonance in a quantum spin dimer system driven by magnetoelectric coupling
- Author
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Mitsuru Akaki, Masayuki Hagiwara, Hidekazu Tanaka, Koichi Kindo, Masashige Matsumoto, and Shojiro Kimura
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Physics ,Condensed matter physics ,Linear polarization ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Coupling (probability) ,01 natural sciences ,Dipole ,Polarization density ,Electric field ,0103 physical sciences ,Condensed Matter::Strongly Correlated Electrons ,Singlet state ,010306 general physics ,0210 nano-technology ,Spin (physics) ,Electric dipole spin resonance - Abstract
In this Rapid Communication, we propose a mechanism for electric dipole active spin resonance caused by spin-dependent electric polarization in a quantum spin gapped system. This proposal was successfully confirmed by high-frequency electron spin resonance (ESR) measurements of the quantum spin dimer system ${\mathrm{KCuCl}}_{3}$. ESR measurements by an illuminating linearly polarized electromagnetic wave reveal that the optical transition between the singlet and triplet states in ${\mathrm{KCuCl}}_{3}$ is driven by an ac electric field. The selection rule of the observed transition agrees with the calculation by taking into account spin-dependent electric polarization. We suggest that spin-dependent electric polarization is effective in achieving fast control of quantum spins by an ac electric field.
- Published
- 2018
19. Magnetism of the spin-1 tetramer compound A2Ni2Mo3O12(A=Rb or K)
- Author
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Koichi Kindo, Masashige Matsumoto, Akira Matsuo, and Masashi Hase
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Physics ,Phase transition ,Magnetism ,Transition temperature ,Order (ring theory) ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Magnetic susceptibility ,Magnetization ,Crystallography ,Quantum critical point ,0103 physical sciences ,Antiferromagnetism ,010306 general physics ,0210 nano-technology - Abstract
We measured the temperature dependence of the magnetic susceptibility $\ensuremath{\chi}(T)$ and the specific heat $C(T)$ and the magnetic-field dependence of the magnetization $M(H)$ of ${A}_{2}{\mathrm{Ni}}_{2}{\mathrm{Mo}}_{3}{\mathrm{O}}_{12}\phantom{\rule{4pt}{0ex}}(A$ = Rb or K) powder. We consider that the probable spin model is an interacting spin-1 antiferromagnetic tetramer model. We evaluated values of the intratetramer interactions as ${J}_{1}=9$ K and ${J}_{2}=18$ K, and the effective intertetramer interaction as ${J}_{\mathrm{eff}}=4$ K for ${\mathrm{Rb}}_{2}{\mathrm{Ni}}_{2}{\mathrm{Mo}}_{3}{\mathrm{O}}_{12}$. The susceptibility and magnetization at 1.3 K of ${\mathrm{K}}_{2}{\mathrm{Ni}}_{2}{\mathrm{Mo}}_{3}{\mathrm{O}}_{12}$ are very close to those of ${\mathrm{Rb}}_{2}{\mathrm{Ni}}_{2}{\mathrm{Mo}}_{3}{\mathrm{O}}_{12}$. We observed a phase transition to a magnetically ordered state in $C(T)/T$ in magnetic fields above 3 T. The transition temperature increases with magnetic field. Probably, the ordered state appears around 1.8 K even in 0 T. The ordered state in 0 T, however, is not stable enough like an order in the vicinity of a quantum critical point. Longitudinal-mode magnetic excitations may be observable in single crystalline ${A}_{2}{\mathrm{Ni}}_{2}{\mathrm{Mo}}_{3}{\mathrm{O}}_{12}\phantom{\rule{4pt}{0ex}}(A$ = Rb or K).
- Published
- 2017
20. Field induced spontaneous quasiparticle decay and renormalization of quasiparticle dispersion in a quantum antiferromagnet
- Author
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Alexander Chernyshev, Tao Hong, K. Coester, H. Agrawal, Mark M. Turnbull, Firas F. Awwadi, Kai Phillip Schmidt, Yiming Qiu, David Tennant, and Masashige Matsumoto
- Subjects
Phonon ,Science ,FOS: Physical sciences ,General Physics and Astronomy ,02 engineering and technology ,Neutron scattering ,Roton ,01 natural sciences ,7. Clean energy ,Article ,General Biochemistry, Genetics and Molecular Biology ,Renormalization ,Condensed Matter::Materials Science ,Condensed Matter - Strongly Correlated Electrons ,0103 physical sciences ,010306 general physics ,Quantum ,Physics ,Condensed Matter - Materials Science ,Multidisciplinary ,Strongly Correlated Electrons (cond-mat.str-el) ,Condensed matter physics ,Condensed Matter::Other ,Magnon ,Materials Science (cond-mat.mtrl-sci) ,General Chemistry ,021001 nanoscience & nanotechnology ,cond-mat.mtrl-sci ,Quantum electrodynamics ,Quasiparticle ,Condensed Matter::Strongly Correlated Electrons ,cond-mat.str-el ,0210 nano-technology ,Excitation - Abstract
The notion of a quasiparticle, such as a phonon, a roton, or a magnon, is used in modern condensed matter physics to describe an elementary collective excitation. The intrinsic zero-temperature magnon damping in quantum spin systems can be driven by the interaction of the one-magnon states and multi-magnon continuum. However, detailed experimental studies on this quantum many-body effect induced by an applied magnetic field are rare. Here we present a high-resolution neutron scattering study in high fields on an S=1/2 antiferromagnet C9H18N2CuBr4. Compared with the non-interacting linear spin-wave theory, our results demonstrate a variety of phenomena including field-induced renormalization of one-magnon dispersion, spontaneous magnon decay observed via intrinsic linewidth broadening, unusual non-Lorentzian two-peak structure in the excitation spectra, and a dramatic shift of spectral weight from one-magnon state to the two-magnon continuum., 8 pages, 6 figures, some typos were corrected in the revised version
- Published
- 2017
21. Magnetoelectric effect in the quantum spin gap system TlCuCl3
- Author
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Masayuki Hagiwara, Hidekazu Tanaka, Y. Sawada, Kento Kakihata, Kazuo Watanabe, Masashige Matsumoto, and Shojiro Kimura
- Subjects
Physics ,Condensed matter physics ,Magnon ,02 engineering and technology ,Quantum entanglement ,021001 nanoscience & nanotechnology ,01 natural sciences ,Ferroelectricity ,Condensed Matter::Materials Science ,Quantum spin Hall effect ,0103 physical sciences ,Quasiparticle ,Condensed Matter::Strongly Correlated Electrons ,010306 general physics ,0210 nano-technology ,Ground state ,Spin (physics) ,Quantum fluctuation - Abstract
Quantum magnets, which involve strong quantum fluctuation stemming from noncommutative properties of spin operators, have attracted much attention because of those fascinating properties. In this paper, we report detailed behaviors of the ferroelectricity, driven by the field-induced Bose-Einstein condensation of magnon quasiparticles in the quantum spin gap system ${\mathrm{TlCuCl}}_{3}$. Superposition of the wave functions inherent in a quantum magnet in its ground state plays a key role in the appearance of this ferroelectricity. The field dependence of the spontaneous electric polarization clearly demonstrates that the ferroelectricity is caused by the emergence of the vector spin chirality in the magnon Bose-Einstein condensate. The ferroelectricity is suggested to be significantly enhanced by quantum entanglement in the spin dimer. Furthermore, reflecting the isotropic nature of ${\mathrm{TlCuCl}}_{3}$, the ferroelectricity is very soft with a low electric coercive field ${E}_{\mathrm{r}}\ensuremath{\simeq}0.03$ MV/m. Our analysis indicates that vector components of the electric polarization, which are not caused by the spin current mechanism, appear in ${\mathrm{TlCuCl}}_{3}$.
- Published
- 2017
22. Magnetism of the antiferromagnetic spin- 32 dimer compound CrVMoO7 having an antiferromagnetically ordered state
- Author
-
Haruhiko Kuroe, Hiroki Yamazaki, Yuta Ebukuro, Koichi Kindo, Taku J. Sato, Masashige Matsumoto, Masashi Hase, Akira Matsuo, and James R. Hester
- Subjects
Physics ,Condensed matter physics ,Magnetism ,Neutron diffraction ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Inelastic neutron scattering ,law.invention ,Magnetization ,law ,0103 physical sciences ,Spin model ,Antiferromagnetism ,Condensed Matter::Strongly Correlated Electrons ,010306 general physics ,0210 nano-technology ,Electron paramagnetic resonance ,Spin-½ - Abstract
We measured magnetization, specific heat, electron spin resonance, neutron diffraction, and inelastic neutron scattering of ${\mathrm{CrVMoO}}_{7}$ powder. An antiferromagnetically ordered state appears below ${T}_{\mathrm{N}}=26.5\ifmmode\pm\else\textpm\fi{}0.8$ K. We consider that the probable spin model for ${\mathrm{CrVMoO}}_{7}$ is an interacting antiferromagnetic spin-$\frac{3}{2}$ dimer model. We evaluated the intradimer interaction $J$ to be $25\ifmmode\pm\else\textpm\fi{}1$ K and the effective interdimer interaction ${J}_{\mathrm{eff}}$ to be $8.8\ifmmode\pm\else\textpm\fi{}1$ K. ${\mathrm{CrVMoO}}_{7}$ is a rare spin dimer compound that shows an antiferromagnetically ordered state at atmospheric pressure and zero magnetic field. The magnitude of ordered moments is $0.73(2){\ensuremath{\mu}}_{\mathrm{B}}$. It is much smaller than a classical value $\ensuremath{\sim}3{\ensuremath{\mu}}_{\mathrm{B}}$. Longitudinal-mode magnetic excitations may be observable in single crystalline ${\mathrm{CrVMoO}}_{7}$.
- Published
- 2017
23. Magnetism of the antiferromagnetic spin-12tetramer compoundCuInVO5
- Author
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Masashige Matsumoto, Akira Matsuo, Koichi Kindo, and Masashi Hase
- Subjects
Physics ,Specific heat ,Condensed matter physics ,Magnetism ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Magnetic susceptibility ,Magnetization ,Tetramer ,0103 physical sciences ,Antiferromagnetism ,Condensed Matter::Strongly Correlated Electrons ,010306 general physics ,0210 nano-technology ,Magnetization plateau ,Spin-½ - Abstract
We measured the temperature dependence of the magnetic susceptibility and specific heat and the magnetic-field dependence of the magnetization of CuInVO$_5$. An antiferromagnetically ordered state appears below $T_{\rm N} = 2.7$ K. We observed a $\frac{1}{2}$ quantum magnetization plateau above 30 T at 1.3 K. We show that the spin system consists of antiferromagnetic spin-$\frac{1}{2}$ tetramers with $J_1 = 240 \pm 20$ and $J_2 = -142 \pm 10$ K for the intratetramer interactions.
- Published
- 2016
24. Roles of Quadrupoles in Non-Fermi Liquid Physics for Crystal Field Triplets
- Author
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Mikito Koga and Masashige Matsumoto
- Subjects
Condensed Matter::Quantum Gases ,Physics ,Crystal ,Dipole ,Magnetic moment ,Condensed matter physics ,Field (physics) ,General Physics and Astronomy ,Condensed Matter::Strongly Correlated Electrons ,Fermi liquid theory ,Fermi gas ,Magnetic dipole ,Inductive coupling - Abstract
Crystal field triplet ground states in f2 configurations such as Pr ions have quadrupolar coupling as well as magnetic coupling to conduction electrons, leading to a nontrivial non-Fermi liquid Kon...
- Published
- 2019
25. Ferroelectricity by Bose–Einstein condensation in a quantum magnet
- Author
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Masayuki Hagiwara, Y. Sawada, Hidekazu Tanaka, K. Watanabe, K. Kakihata, Masashige Matsumoto, and Shojiro Kimura
- Subjects
Josephson effect ,Science ,General Physics and Astronomy ,02 engineering and technology ,01 natural sciences ,Article ,General Biochemistry, Genetics and Molecular Biology ,law.invention ,Superfluidity ,Quantization (physics) ,law ,Quantum mechanics ,0103 physical sciences ,010306 general physics ,Quantum statistical mechanics ,Quantum ,Condensed Matter::Quantum Gases ,Physics ,Multidisciplinary ,Condensed matter physics ,Condensed Matter::Other ,Magnon ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter::Strongly Correlated Electrons ,0210 nano-technology ,Bose–Einstein condensate ,Identical particles - Abstract
The Bose–Einstein condensation is a fascinating phenomenon, which results from quantum statistics for identical particles with an integer spin. Surprising properties, such as superfluidity, vortex quantization or Josephson effect, appear owing to the macroscopic quantum coherence, which spontaneously develops in Bose–Einstein condensates. Realization of Bose–Einstein condensation is not restricted in fluids like liquid helium, a superconducting phase of paired electrons in a metal and laser-cooled dilute alkali atoms. Bosonic quasi-particles like exciton-polariton and magnon in solids-state systems can also undergo Bose–Einstein condensation in certain conditions. Here, we report that the quantum coherence in Bose–Einstein condensate of the magnon quasi particles yields spontaneous electric polarization in the quantum magnet TlCuCl3, leading to remarkable magnetoelectric effect. Very soft ferroelectricity is realized as a consequence of the O(2) symmetry breaking by magnon Bose–Einstein condensation. The finding of this ferroelectricity will open a new window to explore multi-functionality of quantum magnets., Magnons, quantized spin excitations in magnetic materials, may undergo Bose-Einstein condensation into a macroscopic correlated quantum state at low temperature. Here, the authors demonstrate how magnon condensation in quantum magnet TlCuCl3 generates an electrical polarization.
- Published
- 2016
26. Continuous control of local magnetic moment by applied electric field in multiferroicsBa2CoGe2O7
- Author
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Takatsugu Masuda, Shohei Hayashida, Ryousuke Shiina, Jonathan S. White, Masashige Matsumoto, Minoru Soda, Bertrand Roessli, and Martin Månsson
- Subjects
Physics ,Condensed matter physics ,Magnetic moment ,Magnetoelectric effect ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Electron magnetic dipole moment ,Condensed Matter::Materials Science ,Polarization density ,Magnetization ,Magnetic anisotropy ,0103 physical sciences ,Multiferroics ,010306 general physics ,0210 nano-technology ,Magnetic dipole - Abstract
${\mathrm{Ba}}_{2}{\mathrm{CoGe}}_{2}{\mathrm{O}}_{7}$ exhibits a collinear-antiferromagnetic structure with the easy axis along $\ensuremath{\langle}100\ensuremath{\rangle}$ directions and an antiferroelectric order with the polarization axis along the [001] direction. By applying the electric field the magnetic moment rotates from $\ensuremath{\langle}100\ensuremath{\rangle}$ to [110] directions and, simultaneously, the antiferroelectric state changes to the ferroelectric state gradually. This magnetoelectric effect, i.e., continuous control of the local magnetic moment by the electric field, is quantitatively explained by the Hamiltonian including the dielectric energy.
- Published
- 2016
27. Emergent Electric Polarization by Kondo Effect in a Triangular Triple Quantum Dot
- Author
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Hiroaki Kusunose, Mikito Koga, and Masashige Matsumoto
- Subjects
Physics ,Condensed matter physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Strongly Correlated Electrons (cond-mat.str-el) ,Degrees of freedom ,General Physics and Astronomy ,FOS: Physical sciences ,Numerical renormalization group ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Compensation (engineering) ,Polarization density ,Condensed Matter - Strongly Correlated Electrons ,Quantum dot ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Condensed Matter::Strongly Correlated Electrons ,Kondo effect ,Spin-½ - Abstract
A triangular triple quantum dot gives various Kondo effects, such as the emergence of an electric polarization accompanied by a complete compensation of spin degrees of freedom. The interplay of spin and charge of electrons in quantum dots is investigated using an Anderson model with an equilateral triangular spin cluster, in which a single electron state at one site is hybridized with a conduction band in a lead. The numerical renormalization group analysis shows how a nonzero electric polarization develops with local electrons traveling in the loop and how it depends on the hybridization strength as an experimentally controllable parameter in the Kondo effect., Comment: 5 pages, 5 figures
- Published
- 2016
- Full Text
- View/download PDF
28. Magnetic excitations in the spin-12tetramer substanceCu2Cd11411B2O6obtained by inelastic neutron scattering experiments
- Author
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Yukinobu Kawakita, Kenji Nakajima, Masashige Matsumoto, Seiko Ohira-Kawamura, Tatsuya Kikuchi, and Masashi Hase
- Subjects
Physics ,Tetramer ,Spin wave ,Order (ring theory) ,Antiferromagnetism ,Atomic physics ,Condensed Matter Physics ,Ground state ,Inelastic neutron scattering ,Electronic, Optical and Magnetic Materials ,Spin-½ - Abstract
We performed inelastic neutron scattering experiments on ${\mathrm{Cu}}_{2}^{114}\mathrm{Cd}{}^{11}{\text{B}}_{2}{\mathrm{O}}_{6}$ powder. The magnetic excitations at low temperatures are similar to those of the interacting spin-$\frac{1}{2}$ tetramers in the ordered state. The weak excitations existing above 3 meV suggest that the Higgs mode appears in ${\mathrm{Cu}}_{2}{\mathrm{CdB}}_{2}{\mathrm{O}}_{6}$ at ambient pressure and zero magnetic field. We evaluated ${J}_{1}=27.3\ifmmode\pm\else\textpm\fi{}1.0$ and ${J}_{2}=\ensuremath{-}14.0\ifmmode\pm\else\textpm\fi{}1.4$ meV for the intratetramer interactions and ${J}_{3}=\ensuremath{-}0.4\ifmmode\pm\else\textpm\fi{}0.2$ and ${J}_{4}=1.4\ifmmode\pm\else\textpm\fi{}0.2$ meV for the intertetramer interactions. The spin gap in the isolated spin tetramer was calculated to be 1.6 meV, which is less than the effective intertetramer interaction value $(3.6\ifmmode\pm\else\textpm\fi{}0.8$ meV). Therefore, antiferromagnetic long-range order is possible, although the ground state of the isolated spin tetramer is the spin-singlet state. We discuss the temperature dependence of the magnetic excitations.
- Published
- 2015
29. Magnetism of the antiferromagnetic spin-3/2 dimer compound CrVMoO7 having an antiferromagnetically ordered state
- Author
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Masashi, Hase, Yuta, Ebukuro, Haruhiko, Kuroe, Masashige, Matsumoto, Akira, Matsuo, Koichi, Kindo, James, R Hester, Taku, J Sato, and Hiroki, Yamazaki
- Published
- 2018
30. Magnetic properties of the antiferromagnetic spin-${1 \over 2}$ tetramer compound CuInVO5
- Author
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Masashige Matsumoto, Akira Matsuo, Masashi Hase, and Koichi Kindo
- Subjects
Physics ,History ,Condensed matter physics ,Magnetic moment ,Magnetism ,Magnetic susceptibility ,Computer Science Applications ,Education ,Magnetization ,Spin model ,Antiferromagnetism ,Condensed Matter::Strongly Correlated Electrons ,Singlet state ,Spin-½ - Abstract
We measured the temperature dependence of the magnetic susceptibility and specific heat and the magnetic-field dependence of the magnetization of CuInVO5. An antiferromagnetically ordered state appears below T N = 2.7 K. We observed a quantum magnetization plateau above 30 T at 1.3 K. The probable spin model for CuInVO5 is an interacting spin- tetramer model. We evaluated the values of the intratetramer interactions as J 1 = 240 ± 20 K (antiferromagnetic) and J 2 = −142 ± 10 K (ferromagnetic) and the value of the effective intertetramer interaction as J eff = 30 ± 4 K. The ground state of the isolated spin tetramer with the J 1 and J 2 values is spin singlet. The shrinkage of ordered magnetic moments by quantum fluctuation can be expected. Longitudinal-mode magnetic excitations may be observable in CuInVO5.
- Published
- 2018
31. UHV-type synchrotron radiation reflectometer
- Author
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Masashige Matsumoto, Katsuyuki Fukutani, T. Kawauchi, Yoshitaka Yoda, Y. Suetsugu, X. W. Zhang, and Tatsuo Okano
- Subjects
Physics ,Physics::Instrumentation and Detectors ,business.industry ,Astrophysics::High Energy Astrophysical Phenomena ,Feedthrough ,Synchrotron radiation ,Condensed Matter Physics ,Reflectivity ,Surfaces, Coatings and Films ,Bellows ,Optics ,Goniometer ,business ,Instrumentation - Abstract
We designed a reflectometer for grazing-incidence X-ray measurements with a rotational feedthrough consisting of three welded bellows and a circle-type goniometer. This apparatus does not require differential pumping and is suitable for ultra-high-vacuum applications. With this reflectometer, we successfully performed high-precision synchrotron radiation X-ray reflectivity measurements on a thin iron-film under an ultra-high-vacuum condition.
- Published
- 2009
32. Development of micro-beam NRA for 3D-mapping of hydrogen distribution in solids: Application of tapered glass capillary to 6MeV 15N ion
- Author
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Masashige Matsumoto, Takehiko Itoh, Hiroshi Yamashita, Markus Wilde, Iwamura Yasuhiro, Takuya Nebiki, Tadashi Narusawa, Daiichiro Sekiba, Katsuyuki Fukutani, Jirohta Kasagi, Hiroyuki Matsuzaki, S. Ogura, and H. Yonemura
- Subjects
Nuclear and High Energy Physics ,Materials science ,Hydrogen ,Ion beam ,business.industry ,Capillary action ,chemistry.chemical_element ,Substrate (electronics) ,Ion ,Condensed Matter::Soft Condensed Matter ,chemistry ,Quadrupole ,Physics::Accelerator Physics ,Optoelectronics ,Magnetic lens ,Atomic physics ,business ,Instrumentation ,Beam (structure) - Abstract
A micro-beam NRA system, by means of a resonant nuclear reaction 1H(15N, αγ)12C, has been developed for the purpose of the 3D mapping of the hydrogen distribution in solids. To obtain the tens μm size of the beam spot, the combination of the newly proposed tapered glass capillary and a conventional quadrupole magnetic lens is employed. An Y patterned film on a substrate is prepared as an application of the developed system. The 6 MeV 15N beam focused by glass capillaries down to 50 μm successfully shows the hydrogen distribution. The in-plane NRA profile implies that the beam emitted from the glass capillary outlet is parallel, although the original beam has a considerable divergence. The NRA measurements in the 103 Pa N2 atmosphere due to the low gas conductance of the glass capillary is also demonstrated.
- Published
- 2008
33. Doppler analysis of hydrogen motion on Pt(111)–Sn surface alloys using the 1H(15N,αγ)12C nuclear reaction
- Author
-
Markus Wilde, Masashige Matsumoto, Katsuyuki Fukutani, and S. Ogura
- Subjects
Nuclear reaction ,Nuclear and High Energy Physics ,Hydrogen ,Chemistry ,Analytical chemistry ,Resonance ,chemistry.chemical_element ,symbols.namesake ,Adsorption ,Nuclear reaction analysis ,symbols ,Atomic physics ,Instrumentation ,Doppler effect ,Intensity (heat transfer) ,Doppler broadening - Abstract
Hydrogen adsorbed on the Pt(1 1 1)–Sn surface alloys was investigated by nuclear reaction analysis (NRA) using 1H(15N,αγ)12C. The γ-ray intensity profile as a function of the incident ion energy is analyzed on the basis of the Doppler broadening. From the widths of the resonance profiles, the zero-point vibrational energies in the vertical and in-plane directions are estimated to be 78.2 ± 3.7 and 53.6 ± 5.8 meV on Pt(1 1 1)2 × 2–Sn, respectively, and 72.5 ± 3.7 and 58.5 ± 6.7 meV on Pt(1 1 1)√3 × √3–Sn, respectively. The adsorption state and vibrational property of H on the surface alloys are discussed.
- Published
- 2007
34. Magnetic excitations of the spin-1/2 tetramer substance Cu$_2$$^{114}$Cd$^{11}$B$_2$O$_6$ obtained by inelastic neutron scattering experiments
- Author
-
Kenji Nakajima, Masashi Hase, Masashige Matsumoto, Seiko Ohira-Kawamura, Tatsuya Kawahara, and Yukinobu Kawakita
- Subjects
Condensed Matter - Strongly Correlated Electrons ,Strongly Correlated Electrons (cond-mat.str-el) ,FOS: Physical sciences ,Condensed Matter::Strongly Correlated Electrons - Abstract
We performed inelastic neutron scattering experiments on Cu$_2$$^{114}$Cd$^{11}$B$_2$O$_6$ powder. The magnetic excitations at low temperatures are similar to those of the interacting spin-1/2 tetramers in the ordered state. The weak excitations existing above 3 meV suggest that the Higgs mode appears in Cu$_2$CdB$_2$O$_6$ at ambient pressure and zero magnetic field. We evaluated $J_1 = 27.3 \pm 1.0$ and $J_2 = -14.0 \pm 1.4$ meV for the intra-tetramer interactions and $J_3 = -0.4 \pm 0.2$ and $J_4 = 1.4 \pm 0.2$ meV for the inter-tetramer interactions. The spin gap in the isolated spin tetramer was calculated to be 1.6 meV, which is less than the effective inter-tetramer interaction value ($3.6 \pm 0.8$ meV). Therefore, antiferromagnetic long-range order is possible, although the ground state of the isolated spin tetramer is the spin-singlet state. We discuss the temperature dependence of the magnetic excitations., Comment: 9 pages, 7 figures, 1 table
- Published
- 2015
- Full Text
- View/download PDF
35. Growth and vibrational properties of ultra-thin Cr2O3 films grown on Cr(110) studied by RAIRS
- Author
-
H. Hagiwara, Markus Wilde, Teruo Okano, Masashige Matsumoto, Katsuyuki Fukutani, and S. Koya
- Subjects
Phase transition ,Absorption spectroscopy ,Chemistry ,Phonon ,Analytical chemistry ,Infrared spectroscopy ,Surfaces and Interfaces ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Paramagnetism ,Absorption band ,Materials Chemistry ,Antiferromagnetism ,Absorption (electromagnetic radiation) - Abstract
Ultra-thin films of Cr2O3(0 0 0 1) grown on Cr(1 1 0) were investigated by reflection absorption infrared spectroscopy (RAIRS). An absorption band at 720 cm−1 is assigned to a longitudinal optical phonon of Cr2O3. With increasing O2 exposure, this absorption band shifts to higher frequency, which is qualitatively explained by a simple spring model. After successive oxidation with 18O2 and 16O2, two absorption bands corresponding to Cr 2 18 O 3 and Cr 2 16 O 3 were distinctly observed suggesting that oxygen diffusion hardly occurs during the oxide growth. Temperature dependence of the RAIRS spectrum taken from the Cr2O3 film revealed that the absorption band position shifts to lower frequency along with broadening of the band width. Anharmonic coupling with low-frequency phonons and effects of the antiferromagnetic to paramagnetic phase transition are discussed.
- Published
- 2006
36. Phase transitions on Cr2O3 thin films grown on Cr(110)
- Author
-
Katsuyuki Fukutani, Markus Wilde, Masashige Matsumoto, Teruo Okano, and T. Takano
- Subjects
Phase transition ,Materials science ,Oxide ,Bioengineering ,Surfaces and Interfaces ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Sample temperature ,Crystallography ,chemistry.chemical_compound ,Electron diffraction ,chemistry ,Mechanics of Materials ,Chromium oxide ,Thin film ,Metal–insulator transition ,Biotechnology - Abstract
Ultra-thin films of Cr2O3(0001) grown on Cr(110) were investigated by low-energy electron diffraction (LEED). Two samples with different oxide thicknesses were prepared. For the 5 nm-thick film, LEED revealed that the structure changes from 1×1 at 300 K to √3×√3 at 150 K and 1×1 at 100 K, which is in good agreement with a previous study. For the film thicker than 10 nm, LEED spot intensities were found to change with the sample temperature. LEED I-V curves shifted towards higher energy at 100 K compared to 300 K, which is attributed to a change of the mean inner potential. The origin of this change of the mean inner potential is discussed. [DOI: 10.1380/ejssnt.2006.534]
- Published
- 2006
37. Symmetry Analysis of Magnetoelectric Effects in Honeycomb Antiferromagnet Co4Nb2O9.
- Author
-
Masashige Matsumoto and Mikito Koga
- Abstract
Magnetoelectric effects in honeycomb antiferromagnet Co
4 Nb2 O9 are investigated on the basis of symmetry analyses of Co2+ ions in trigonal P3¯c1 space group. For each Co2+ ion, the possible spin dependence is classified by C3 point-group symmetry. This accounts for the observed main effect that an electric polarization rotates in the opposite direction at the twice speed relative to the rotation of the external magnetic field applied in the ab-plane. Inversion centers and twofold axes in the unit cell restrict the active spin-dependence of the electric polarization, which well explains the observed experimental results. Expected optical properties of quadrupolar excitation and various types of dichroism are also discussed. [ABSTRACT FROM AUTHOR]- Published
- 2019
- Full Text
- View/download PDF
38. Exciton-Mediated Triplet Superconductivity in Th System PrOs4Sb12
- Author
-
Mikito Koga and Masashige Matsumoto
- Subjects
Physics ,Superconductivity ,Strongly Correlated Electrons (cond-mat.str-el) ,Condensed matter physics ,Component (thermodynamics) ,Condensed Matter - Superconductivity ,Exciton ,Degrees of freedom (physics and chemistry) ,FOS: Physical sciences ,General Physics and Astronomy ,Electron ,Symmetry (physics) ,Superconductivity (cond-mat.supr-con) ,Condensed Matter - Strongly Correlated Electrons ,Pairing ,Singlet state - Abstract
In PrOs4Sb12, the lowest-lying singlet and triplet states in a Pr 4f^2 configuration hybridize with conduction electrons having local a_u and t_u point-group symmetries. It is shown that for an attractive triplet pairing interaction, the orbital degrees of freedom of the t_u component are important. In addition, the Th point-group symmetry characteristic of skutterudites plays an important role in stabilizing triplet superconductivity., 4 pages, 2 figures
- Published
- 2005
39. The Soft Mode Transition Induced by Magnetic Field and Pressure in TlCuCl3and Related Dimer Compounds
- Author
-
Bruce Normand, T. M. Rice, Manfred Sigrist, and Masashige Matsumoto
- Subjects
Physics ,Quantum phase transition ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,Superexchange ,Magnon ,Hydrostatic pressure ,Condensed Matter::Strongly Correlated Electrons ,Soft modes ,Quantum spin liquid ,Excitation ,Spin-½ - Abstract
TlCuCl 3 is an example of a quantum spin liquid of S = 1/2 Cu 2+ dimers. Strong inter-dimer superexchange interactions give rise to a three-dimensional dispersion of the triplet magnon. The minimum excitation energy determines the spin gap which is significantly smaller than the dimer coupling. It can be closed by an applied hydrostatic pressure of the order of 1 kbar or by a magnetic field of 5.6 T, offering a unique opportunity to study the evolution of the magnon modes through the pressure- and field-induced quantum phase transitions.
- Published
- 2005
40. Superconductivity Mediated by Spin Dimer Singlet-Triplet Excitation
- Author
-
Masashige Matsumoto and Mikito Koga
- Subjects
Superconductivity ,Physics ,Physics and Astronomy (miscellaneous) ,Spin states ,Condensed matter physics ,Spin polarization ,Diradical ,Condensed Matter::Superconductivity ,Condensed Matter::Strongly Correlated Electrons ,Singlet state ,Triplet state ,Ground state ,Spin-½ - Abstract
The ground state of a spin dimer system is a non-magnetic singlet accompanied by dispersive triplet excitations. We introduce a conduction electron system coupled to spin dimers. The triplet excitations generate spin fluctuations, giving rise to an attractive interaction between conduction electrons. We study superconductivity mediated by the spin dimer triplet excitations with a simple two-dimensional model, and discuss a possibility of unconventional superconductivity.
- Published
- 2005
41. Ground-State Phase Diagram of the S=1/2 Distorted Diamond Type Spin Chain with Ferromagnetic Interactions
- Author
-
Tsutoshi Yamada, Mikito Koga, Masashige Matsumoto, Kiyomi Okamoto, Takashi Tonegawa, and Tôru Sakai
- Subjects
Physics ,Diamond type ,Physics and Astronomy (miscellaneous) ,Field (physics) ,Ferromagnetism ,Condensed matter physics ,Ground state ,Plateau (mathematics) ,Spin chain ,Phase diagram ,Magnetic field - Abstract
We investigate, analytically and numerically, the ground state of the S = 1/2 distorted diamond type spin chain having three kinds of couplings, where one or two types of the couplings are ferromagnetic. We obtained the phase diagram at zero-magnetic field and also at M s /3, where M s is the saturation magnetization. We also discuss the plateau at (2/3)M s .
- Published
- 2005
42. Magnetic-field-induced odd-frequency superconductivity in s-wave superconductors
- Author
-
Masashige Matsumoto, Hiroaki Kusunose, and Mikito Koga
- Subjects
Superconductivity ,Physics ,Basis (linear algebra) ,Condensed matter physics ,Quantum mechanics ,S-wave ,General Physics and Astronomy ,Fermion ,Cooper pair ,Wave function ,Symmetry (physics) ,Magnetic field - Abstract
The wavefunction of the Cooper pair of the conventional BCS state is characterized by an evenparity (s-wave) spin-singlet state. An external magnetic field is well known to modify the wavefunction of the Cooper pair and to break the conventional BCS superconducting state. We find that the wavefunction of the modified Cooper pair contains a spin-triplet component with s-wave orbital symmetry. While the spin-triplet s-wave Cooper pair is forbidden owing to the fermion property, it is permitted in the generalized theoretical framework containing an odd-frequency dependence of the order parameter. We investigate this point on the basis of the self-consistent calculation in the Eliashberg theory and find that the odd-frequency order parameter coexists with the evenfrequency one. We also report how the physical properties are affected by the induced odd-frequency superconducting order parameter.
- Published
- 2013
43. Crystal-Field Excitations, Magnetic-Field-Induced Phase Transition and Neutron-Scattering Spectra in PrOs4Sb12
- Author
-
Ryousuke Shiina, Mikito Koga, and Masashige Matsumoto
- Subjects
Physics ,Phase transition ,Field (physics) ,Condensed matter physics ,Spin wave ,Quadrupole ,General Physics and Astronomy ,Electron ,Neutron scattering ,Inelastic scattering ,Magnetic field - Abstract
One possible origin of the field-induced ordered phase (FIOP) in PrOs 4 Sb 12 is an interaction of quadrupolar moments of Pr 4 f electrons in the singlet–triplet crystal-field (CF) levels. We study...
- Published
- 2004
44. Anomalous flux flow resistivity of MgB2
- Author
-
S. Lee, S. Tajima, Yasuhiro H. Matsuda, Masashige Matsumoto, K. Izawa, and A. Shibata
- Subjects
Physics ,Superconductivity ,Field (physics) ,Condensed matter physics ,Energy Engineering and Power Technology ,Field dependence ,Tourbillon ,Dissipation ,Vorticity ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Vortex ,Electrical resistivity and conductivity ,Condensed Matter::Superconductivity ,Electrical and Electronic Engineering - Abstract
We measured the flux flow resistivity ρ f associated with a purely viscous motion of the vortices in high-quality MgB 2 by the microwave surface impedance. The flux flow resistivity exhibits unusual field dependence with strong enhancement at low fields, which is markedly different from that in conventional s-wave superconductors. A crossover field which separates two distinct flux flow regime with different slope of ρ f was observed in H ∥ ab -plane. The unusual H -dependence indicates that two very differently sized superconducting gaps in MgB 2 manifest themselves clearly in the vortex dynamics and nearly equally contribute to the energy dissipation.
- Published
- 2004
45. Hydrogen adsorption on Ag and Au monolayers grown on Pt(1 1 1)
- Author
-
Katsuyuki Fukutani, Teruo Okano, S. Ogura, Markus Wilde, Michio Okada, Wilson Agerico Diño, Toshio Kasai, and Masashige Matsumoto
- Subjects
Hydrogen ,Thermal desorption spectroscopy ,Chemistry ,Analytical chemistry ,chemistry.chemical_element ,Surfaces and Interfaces ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Adsorption ,Chemisorption ,Nuclear reaction analysis ,Desorption ,Monolayer ,Materials Chemistry ,Thin film - Abstract
We report experimental results on the interaction of hydrogen with monolayer thin Ag and Au films grown on a Pt(1 1 1) substrate, measured with thermal desorption spectroscopy (TDS) and nuclear reaction analysis (NRA). We found that H2 dissociative adsorption is activated on both thin film surfaces. Atomic hydrogen was found to adsorb on the Ag and Au films on Pt(1 1 1) with main desorption temperatures of 160 and 120 K, respectively. The monolayer thin Ag and Au films on Pt(1 1 1) are chemically similar to the (1 1 1) surfaces of bulk Ag and Au, respectively.
- Published
- 2004
46. Theory of Kondo Effect in Spin Triplet Superconductors
- Author
-
Mikito Koga and Masashige Matsumoto
- Subjects
Superconductivity ,Physics ,Nuclear and High Energy Physics ,Spin polarization ,Condensed matter physics ,Kondo insulator ,Nuclear Energy and Engineering ,Condensed Matter::Superconductivity ,Quantum mechanics ,Condensed Matter::Strongly Correlated Electrons ,Kondo effect ,Triplet state ,Cooper pair ,Ground state ,Spin-½ - Abstract
We study the Kondo effect in a px + ipy-wave superconductor using the Wilson's numerical renormalization group method. For this triplet superconductor with a full energy gap, the ground state is always a spin doublet, which is different from the case of s-wave superconductors. The calculated magnetic susceptibility shows that a local spin is shrunk by the Kondo effect and that the spin of the ground state is generated by the orbital effect of the px + ipy-wave Cooper pairs. We also discuss the effect of spin polarization of the triplet superconductor.
- Published
- 2002
47. Dynamical low-energy electron diffraction analysis of the structure of nitric oxide on Pt(111)
- Author
-
Katsuyuki Fukutani, Teruo Okano, N. Tatsumi, and Masashige Matsumoto
- Subjects
Low-energy electron diffraction ,Chemistry ,Bent molecular geometry ,Infrared spectroscopy ,Mineralogy ,Surfaces and Interfaces ,Condensed Matter Physics ,Molecular physics ,Surfaces, Coatings and Films ,Electron diffraction ,Chemisorption ,Molecular vibration ,Materials Chemistry ,Density functional theory ,Absorption (electromagnetic radiation) - Abstract
The adsorption structure of NO on the Pt(1 1 1) surface at low temperature (90–130 K) was studied by dynamical analysis of low-energy electron diffraction and reflection absorption infrared spectroscopy. Three different 2×2 patterns were identified and their experimental intensity vs. voltage curves ( I – V curves) were compared with dynamically calculated I – V curves for the models including the tilted (bent) NO geometry. The differences of I – V curves can be recognized by virtue of the wider incident electron energy range than the previous dynamical analysis. The most promising interpretation is that NO occupies three sites sequentially depending on the NO coverage. In this interpretation, NO first adsorbs at the threefold fcc hollow site, next at the atop site and last at the threefold hcp hollow site. The NO saturation coverage is 0.75 ML ( 1 ML =1.5×10 −15 molecules/cm 2 ). The NO species at the atop site is tilted and those at both hollow sites are upright. Our new model agrees well with the recent density functional theory calculation and explains the experimental results better than the previous model, in which NO transits from the bridge site to the atop site with increasing coverage.
- Published
- 2002
48. Nonvanishing Local Moment in Triplet Superconductors
- Author
-
Mikito Koga and Masashige Matsumoto
- Subjects
Superconductivity ,Physics ,Strongly Correlated Electrons (cond-mat.str-el) ,Spin polarization ,Condensed matter physics ,Condensed Matter - Superconductivity ,FOS: Physical sciences ,General Physics and Astronomy ,Type (model theory) ,Magnetic susceptibility ,Superconductivity (cond-mat.supr-con) ,Condensed Matter - Strongly Correlated Electrons ,Condensed Matter::Superconductivity ,Condensed Matter::Strongly Correlated Electrons ,Kondo effect ,Cooper pair ,Ground state ,Spin-½ - Abstract
The Kondo effect in a $p_x + {\rm i} p_y$-wave superconductor is studied by applying the Wilson's numerical renormalization group method. In this type of superconductor with a full energy gap like a s-wave one, the ground state is always a spin doublet, while a local spin is shrunk by the Kondo effect. The calculated magnetic susceptibility indicates that the spin of the ground state is generated by the orbital effect of the $p_x + {\rm i} p_y$-wave Cooper pairs. The effect of spin polarization of the triplet superconductor is also discussed., 5 pages, 4 figures, to be published in J. Phys. Soc. Jpn
- Published
- 2002
49. Antisymmetric Spin–Orbit Coupling Effect on Kondo-Induced Electric Polarization in a Triangular Triple Quantum Dot
- Author
-
Hiroaki Kusunose, Masashige Matsumoto, and Mikito Koga
- Subjects
Physics ,Strongly Correlated Electrons (cond-mat.str-el) ,Condensed Matter - Mesoscale and Nanoscale Physics ,Spins ,Condensed matter physics ,FOS: Physical sciences ,General Physics and Astronomy ,02 engineering and technology ,Spin–orbit interaction ,Electron ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,021001 nanoscience & nanotechnology ,01 natural sciences ,Condensed Matter - Strongly Correlated Electrons ,Polarization density ,Quantum dot ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,0103 physical sciences ,Diamagnetism ,Condensed Matter::Strongly Correlated Electrons ,Kondo effect ,010306 general physics ,0210 nano-technology ,Anderson impurity model - Abstract
We study the local antisymmetric spin-orbit (ASO) coupling effect on spin, orbital, and charge degrees of freedom for the Kondo effect in a triangular triple quantum dot (TTQD). Here, one of the three QDs is coupled to a metallic lead through electron tunneling, and a local electric polarization is induced by the Kondo effect. The ASO interaction is introduced in the other two coupled QDs on the opposite side of the lead. Generally, the ASO coupling effect is very weak and not easily detectable, but it essentially causes spin and charge reconfigurations in the TTQD through the Kondo effect. Using an extended Anderson model for the TTQD Kondo system, we elucidate that the ASO coupling gives rise to a considerable reduction of the emergent electric polarization, as a consequence of the parity mixing of molecular orbitals in the triangular loop as well as the spin-up and spin-down coupling of local electrons. The latter leads to a local diamagnetic susceptibility owing to the ASO coupled spins. We also show that the Kondo-induced electric polarization can be controlled by the ASO coupling as well as by the magnetic flux penetrating through the TTQD., 11 pages, 5 figures
- Published
- 2017
50. Symmetry Analysis of Spin-Dependent Electric Dipole and Its Application to Magnetoelectric Effects
- Author
-
Mikito Koga, Masashige Matsumoto, and Kosuke Chimata
- Subjects
Physics ,Condensed Matter - Materials Science ,Strongly Correlated Electrons (cond-mat.str-el) ,Magnetic moment ,Condensed matter physics ,Spins ,Point reflection ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,General Physics and Astronomy ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Condensed Matter - Strongly Correlated Electrons ,Dipole ,Electric dipole moment ,0103 physical sciences ,Quadrupole ,Condensed Matter::Strongly Correlated Electrons ,Multiferroics ,010306 general physics ,0210 nano-technology ,Excitation - Abstract
Spin-dependent electric dipole operators are investigated group-theoretically for the emergence of an electric dipole induced by a single spin or by two spins, where the spin dependences are completely classified up to the quadratic order. For a single spin, a product of spin operators behaves as an even-parity electric quadrupole operator, which differs from an odd-parity electric dipole. The lack of the inversion symmetry allows the even- and odd-parity mixing, which leads to the electric dipole described by the electric quadruple operators. Point-group tables are given for classification of the possible spin-dependent electric dipoles and for the qualitative analysis of multiferroic properties, such as an emergent electric dipole moment coexisting with a magnetic moment, electromagnon excitation, and directional dichroism. The results can be applied to a magnetic ion in crystals or embedded in molecules at a site without the inversion symmetry. In the presence of an inversion symmetry, the electric dipole does not appear for a single spin. This is not the case for the electric dipole induced by two spins with antisymmetric spin dependence, which is known as vector spin chirality, in the presence of the inversion center between the two spins. In the absence of the inversion center, symmetric spin-dependent electric dipoles are also relevant. The detailed analysis of various symmetries of two-spin states is applied to spin dimer systems and the related multiferroic properties., Comment: 28 pages, 9 figures
- Published
- 2017
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