111 results on '"Huebl, Hans"'
Search Results
2. Reduced effective magnetization and damping by slowly relaxing impurities in strained γ-Fe2O3 thin films.
- Author
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Müller, Manuel, Scheufele, Monika, Gückelhorn, Janine, Flacke, Luis, Weiler, Mathias, Huebl, Hans, Gepraegs, Stephan, Gross, Rudolf, and Althammer, Matthias
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SUPERCONDUCTING quantum interference devices ,THIN films ,PERPENDICULAR magnetic anisotropy ,MAGNETIZATION ,MAGNETIC transitions ,MAGNETIC properties - Abstract
Magnetically ordered insulators are of key interest for spintronics applications, but most of them have not yet been explored in depth regarding their magnetic properties, in particular with respect to their dynamic response. We study the static and dynamic magnetic properties of epitaxially strained γ -Fe
2 O3 (maghemite) thin films grown via pulsed-laser deposition on MgO substrates by SQUID magnetometry and cryogenic broadband ferromagnetic resonance experiments. SQUID magnetometry measurements reveal hysteretic magnetization curves for magnetic fields applied both in- and out of the sample plane. From the magnetization dynamics of our thin films, we find a small negative effective magnetization in agreement with a strain induced perpendicular magnetic anisotropy. Moreover, we observe a non-linear evolution of the ferromagnetic resonance-linewidth as a function of the microwave frequency and explain this finding with the so-called slow relaxor model. We investigate the magnetization dynamics and non-linear damping mechanisms present in our samples as a function of frequency and temperature and in particular, observe a sign change in the effective magnetization from the transition of the magnetic anisotropy from a perpendicular easy axis to an easy in-plane anisotropy for reduced temperatures. Its nonlinear damping properties and strain-induced perpendicular anisotropy render γ -Fe2 O3 an interesting material platform for spintronics devices. [ABSTRACT FROM AUTHOR]- Published
- 2022
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3. Sideband-resolved resonator electromechanics based on a nonlinear Josephson inductance probed on the single-photon level
- Author
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Schmidt, Philip, T. Amawi, Mohammad, Pogorzalek, Stefan, Deppe, Frank, Marx, Achim, Gross, Rudolf, and Huebl, Hans
- Published
- 2020
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4. Effect of interfacial oxidation layer in spin pumping experiments on Ni80Fe20/SrIrO3 heterostructures.
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Suraj, T. S., Müller, Manuel, Gelder, Sarah, Geprägs, Stephan, Opel, Matthias, Weiler, Mathias, Sethupathi, K., Huebl, Hans, Gross, Rudolf, Ramachandra Rao, M. S., and Althammer, Matthias
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FERROMAGNETIC resonance ,TORQUE control ,THIN films ,MAGNETIC properties ,TORQUE ,ANTIFERROMAGNETIC materials ,SPIN-orbit interactions - Abstract
SrIrO 3 with its large spin–orbit coupling and low charge conductivity has emerged as a potential candidate for efficient spin–orbit torque magnetization control in spintronic devices. Here we report on the influence of an interfacial oxide layer on spin pumping experiments in Ni 80 Fe 20 (NiFe)/SrIrO 3 bilayer heterostructures. To investigate this scenario, we have carried out broadband ferromagnetic resonance (BBFMR) measurements, which indicate the presence of an interfacial antiferromagnetic oxide layer. We performed in-plane BBFMR experiments at cryogenic temperatures, which allowed us to simultaneously study dynamic spin pumping properties (Gilbert damping) and static magnetic properties (such as the effective magnetization and magnetic anisotropy). The results for NiFe/SrIrO 3 bilayer thin films were analyzed and compared to those from a NiFe/NbN/SrIrO 3 trilayer reference sample, where a spin-transparent, ultra-thin NbN layer was inserted to prevent the oxidation of NiFe. At low temperatures, we observe substantial differences in the magnetization dynamics parameters of these samples. In particular, the Gilbert damping in the NiFe/SrIrO 3 bilayer sample drastically increases below 50 K , which can be well explained by enhanced spin fluctuations at the antiferromagnetic ordering temperature of the interfacial oxide layer. Our results emphasize that this interfacial oxide layer plays an important role for the spin current transport across the NiFe/SrIrO 3 interface. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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5. Spin Hall magnetoresistance in antiferromagnetic insulators.
- Author
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Geprägs, Stephan, Opel, Matthias, Fischer, Johanna, Gomonay, Olena, Schwenke, Philipp, Althammer, Matthias, Huebl, Hans, and Gross, Rudolf
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MAGNETORESISTANCE ,MAGNETIC fields ,MAGNETOELASTIC effects ,ANOMALOUS Hall effect ,MAGNETIZATION ,ANTIFERROMAGNETIC materials ,FERROMAGNETIC materials ,QUANTUM Hall effect - Abstract
Antiferromagnetic materials promise improved performance for spintronic applications as they are robust against external magnetic field perturbations and allow for faster magnetization dynamics compared to ferromagnets. The direct observation of the antiferromagnetic state, however, is challenging due to the absence of a macroscopic magnetization. Here, we show that the spin Hall magnetoresistance (SMR) is a versatile tool to probe the antiferromagnetic spin structure via simple electrical transport experiments by investigating the easy-plane antiferromagnetic insulators α − Fe 2 O 3 (hematite) and NiO in bilayer heterostructures with a Pt heavy-metal top electrode. While rotating an external magnetic field in three orthogonal planes, we record the longitudinal and the transverse resistivities of Pt and observe characteristic resistivity modulations consistent with the SMR effect. We analyze both their amplitude and phase and compare the data to the results from a prototypical collinear ferrimagnetic Y 3 Fe 5 O 12 /Pt bilayer. The observed magnetic field dependence is explained in a comprehensive model, based on two magnetic sublattices and taking into account magnetic field-induced modifications of the domain structure. Our results show that the SMR allows us to understand the spin configuration and to investigate magnetoelastic effects in antiferromagnetic multi-domain materials. Furthermore, in α − Fe 2 O 3 /Pt bilayers, we find an unexpectedly large SMR amplitude of 2.5 × 10 − 3 , twice as high as for prototype Y 3 Fe 5 O 12 /Pt bilayers, making the system particularly interesting for room-temperature antiferromagnetic spintronic applications. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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6. An all-electrical torque differential magnetometer operating under ambient conditions
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Kamra, Akashdeep, von Hoesslin, Stefan, Roschewsky, Niklas, Lotze, Johannes, Schreier, Michael, Gross, Rudolf, Goennenwein, Sebastian T.B., and Huebl, Hans
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- 2015
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7. Magnetoelasticity of Co25Fe75 thin films.
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Schwienbacher, Daniel, Pernpeintner, Matthias, Liensberger, Lukas, Edwards, Eric R. J., Nembach, Hans T., Shaw, Justin M., Weiler, Mathias, Gross, Rudolf, and Huebl, Hans
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THIN films ,MAGNETOSTRICTION ,HYBRID systems ,MAGNONS ,NANOMECHANICS ,RESONATORS - Abstract
We investigate the magnetoelastic properties of C o 25 F e 75 and C o 10 F e 90 thin films by measuring the mechanical properties of a doubly clamped string resonator covered with multilayer stacks containing these films. For the magnetostrictive constants, we find λ C o 25 F e 75 = (− 20.68 ± 0.25) × 10 − 6 and λ C o 10 F e 90 = (− 9.80 ± 0.12) × 10 − 6 at room temperature, in contrast to the positive magnetostriction previously found in bulk CoFe crystals. C o 25 F e 75 thin films unite low damping and sizable magnetostriction and are thus a prime candidate for micromechanical magnonic applications, such as sensors and hybrid phonon-magnon systems. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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8. Single-shot readout of an electron spin in silicon
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Morello, Andrea, Pla, Jarryd J., Zwanenburg, Floris A., Chan, Kok W., Tan, Kuan Y., Huebl, Hans, Mottonen, Mikko, Nugroho, Christopher D., Yang, Changyi, van Donkelaar, Jessica A., Alves, Andrew D.C., Jamieson, David N., Escott, Christopher C., Hollenberg, Lloyd C.L., Clark, Robert G., and Dzurak, Andrew S.
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Electron spin -- Research ,Silicon -- Atomic properties -- Research ,Environmental issues ,Science and technology ,Zoology and wildlife conservation - Abstract
The size of silicon transistors used in microelectronic devices is shrinking to the level at which quantum effects become important (1). Although this presents a significant challenge for the further scaling of microprocessors, it provides the potential for radical innovations in the form of spin-based quantum computers (2-4) and spintronic devices (5). An electron spin in silicon can represent a well-isolated quantum bit with long coherence times (6) because of the weak spin-orbit coupling (7) and the possibility of eliminating nuclear spins from the bulk crystal (8). However, the control of single electrons in silicon has proved challenging, and so far the observation and manipulation of a single spin has been impossible. Here we report the demonstration of single-shot, time-resolved readout of an electron spin in silicon. This has been performed in a device consisting of implanted phosphorus donors (9) coupled to a metaloxide-semiconductor single-electron transistor (10,11)--compatible with current microelectronic technology. We observed a spin lifetime of ~6 seconds at a magnetic field of 1.5 tesla, and achieved a spin readout fidelity better than 90 per cent. High-fidelity single-shot spin readout in silicon opens the way to the development of a new generation of quantum computing and spintronic devices, built using the most important material in the semiconductor industry., The projective, single-shot readout of a qubit is a crucial step in both circuit-based and measurement-based quantum computers (12). For electron spins in the solid state, this has only been [...]
- Published
- 2010
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9. Antiferromagentic resonance detected by direct current voltages in MnF2/Pt bilayers.
- Author
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Ross, Philipp, Schreier, Michael, Lotze, Johannes, Huebl, Hans, Gross, Rudolf, and Goennenwein, Sebastian T. B.
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ANTIFERROMAGNETIC materials ,ELECTRIC potential ,RESONANCE ,ELECTRIC insulators & insulation ,WAVEGUIDES - Abstract
We performed coplanar waveguide-based broadband ferromagnetic resonance experiments on the antiferromagnetic insulator MnF
2 , while simultaneously recording the DC voltage arising in a thin platinum film deposited onto the MnF2 . The antiferromagnetic resonance is clearly reflected in both the transmission through the waveguide as well as the DC voltage in the Pt strip. The DC voltage remains largely unaffected by field reversal and thus presumably stems from microwave rectification and/or heating effects. However, we identify a small magnetic field orientation dependent contribution, compatible with antiferromagnetic spin pumping theory. [ABSTRACT FROM AUTHOR]- Published
- 2015
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10. Quantifying the spin mixing conductance of EuO/W heterostructures by spin Hall magnetoresistance experiments.
- Author
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Rosenberger, Paul, Opel, Matthias, Geprägs, Stephan, Huebl, Hans, Gross, Rudolf, Müller, Martina, and Althammer, Matthias
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HETEROSTRUCTURES ,THIN films ,MAGNITUDE (Mathematics) ,TEMPERATURE measurements ,FERROMAGNETIC materials ,SPIN waves - Abstract
The spin Hall magnetoresistance (SMR) allows to investigate the magnetic textures of magnetically ordered insulators in heterostructures with normal metals by magnetotransport experiments. We here report the observation of the SMR in in situ prepared ferromagnetic EuO/W thin film bilayers with magnetically and chemically well-defined interfaces. We characterize the magnetoresistance effects utilizing angle-dependent and field-dependent magnetotransport measurements as a function of temperature. Applying the established SMR model, we derive and quantify the real and imaginary parts of the complex spin mixing interface conductance. We find that the imaginary part is by one order of magnitude larger than the real part. Both decrease with increasing temperature. This reduction is in agreement with thermal fluctuations in the ferromagnet. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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11. High spin-wave propagation length consistent with low damping in a metallic ferromagnet.
- Author
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Flacke, Luis, Liensberger, Lukas, Althammer, Matthias, Huebl, Hans, Geprägs, Stephan, Schultheiss, Katrin, Buzdakov, Aleksandr, Hula, Tobias, Schultheiss, Helmut, Edwards, Eric R. J., Nembach, Hans T., Shaw, Justin M., Gross, Rudolf, and Weiler, Mathias
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SPIN waves ,BRILLOUIN scattering ,FERROMAGNETIC resonance ,FERROMAGNETIC materials ,LIGHT scattering ,MAGNETIC properties - Abstract
We report ultralow intrinsic magnetic damping in Co
25 Fe75 heterostructures, reaching the low 10−4 regime at room temperature. By using a broadband ferromagnetic resonance technique in out-of-plane geometry, we extracted the dynamic magnetic properties of several Co25 Fe75 -based heterostructures with varying ferromagnetic layer thicknesses. By measuring radiative damping and spin pumping effects, we found the intrinsic damping of a 26 nm thick sample to be α 0 ≲ 3.18 × 10 − 4 . Furthermore, using Brillouin light scattering microscopy, we measured spin-wave propagation lengths of up to (21 ± 1) μm in a 26 nm thick Co25 Fe75 heterostructure at room temperature, which is in excellent agreement with the measured damping. [ABSTRACT FROM AUTHOR]- Published
- 2019
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12. Role of interface quality for the spin Hall magnetoresistance in nickel ferrite thin films with bulk-like magnetic properties.
- Author
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Althammer, Matthias, Singh, Amit Vikram, Wimmer, Tobias, Galazka, Zbigniew, Huebl, Hans, Opel, Matthias, Gross, Rudolf, and Gupta, Arunava
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MAGNETIC films ,NICKEL ferrite ,THIN films ,MAGNETIC properties ,MAGNETORESISTANCE ,ZINC ferrites ,FERRITES - Abstract
We utilized spin Hall magnetoresistance (SMR) measurements to experimentally investigate pure spin current transport in thin film heterostructures of nickel ferrite (NiFe
2 O4 ,NFO) and normal metals (NM) Ta and Pt. We grew (001)-oriented NFO thin films by pulsed laser deposition on lattice-matched magnesium gallate (MgGa2 O4 ) substrates, thereby significantly improving their magnetic and structural properties. We performed SMR measurements at room temperature in patterned Hall bar structures for charge currents applied in the [100]- and [110]-directions of NFO. We found that the extracted SMR magnitude for NFO/Pt heterostructures depends crucially on the Pt resistivity of the investigated Hall bar structure. We further study this resistivity scaling of the SMR effect at different temperatures for NFO/Pt. Our results suggest that the spin mixing conductance of the NFO/Pt interface and the Pt resistivity depend on the interface quality and thus a correlation between these two quantities exists. [ABSTRACT FROM AUTHOR]- Published
- 2019
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13. Ultrawide-range photon number calibration using a hybrid system combining nano-electromechanics and superconducting circuit quantum electrodynamics.
- Author
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Schmidt, Philip, Schwienbacher, Daniel, Pernpeintner, Matthias, Wulschner, Friedrich, Deppe, Frank, Marx, Achim, Gross, Rudolf, and Huebl, Hans
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PHOTON counting ,COPLANAR waveguides ,SUPERCONDUCTING circuits ,HYBRID systems ,ELECTROMECHANICAL devices ,QUANTUM electrodynamics - Abstract
We present a hybrid system consisting of a superconducting coplanar waveguide resonator coupled to a nanomechanical string and a transmon qubit acting as a nonlinear circuit element. We perform spectroscopy for both the transmon qubit and the nanomechanical string. Measuring the ac-Stark shift on the transmon qubit and the electromechanically induced absorption on the string allows us to determine the average photon number in the microwave resonator in both the low and high power regimes. In this way, we measure photon numbers that are up to nine orders of magnitude apart. We find a quantitative agreement between the calibrations of photon numbers in the microwave resonator using the two methods. Our experiments demonstrate the combination of superconducting circuit quantum electrodynamics and nano-electromechanics on a single chip. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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14. Temperature dependence of the non-local spin Seebeck effect in YIG/Pt nanostructures.
- Author
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Ganzhorn, Kathrin, Wimmer, Tobias, Cramer, Joel, Schlitz, Richard, Geprägs, Stephan, Jakob, Gerhard, Gross, Rudolf, Huebl, Hans, Kläui, Mathias, and Goennenwein, Sebastian T. B.
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SEEBECK effect ,THERMOELECTRICITY ,YTTRIUM iron garnet ,PLATINUM ,NANOSTRUCTURES - Abstract
We study the transport of thermally excited non-equilibrium magnons through the ferrimagnetic insulator YIG using two electrically isolated Pt strips as injector and detector. The diffusing magnons induce a non-local inverse spin Hall voltage in the detector corresponding to the so-called non-local spin Seebeck effect (SSE). We measure the non-local SSE as a function of temperature and strip separation. In experiments at room temperature we observe a sign change of the non-local SSE voltage at a characteristic strip separation d
0 , in agreement with previous investigations. At lower temperatures however, we find a strong temperature dependence of d0 . This suggests that both the angular momentum transfer across the YIG/Pt interface as well as the transport mechanism of the magnons in YIG as a function of temperature must be taken into account to describe the non-local SSE. [ABSTRACT FROM AUTHOR]- Published
- 2017
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15. Magnon Mode Selective Spin Transport in Compensated Ferrimagnets.
- Author
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Cramer, Joel, Er-Jia Guo, Geprägs, Stephan, Kehlberger, Andreas, Ivanov, Yurii P., Ganzhorn, Kathrin, Della Coletta, Francesco, Althammer, Matthias, Huebl, Hans, Gross, Rudolf, Kosel, Jürgen, Kläui, Mathias, and Goennenwein, Sebastian T. B.
- Published
- 2017
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16. Spin injection into silicon detected by broadband ferromagnetic resonance spectroscopy.
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Ryo Ohshima, Klingler, Stefan, Dushenko, Sergey, Yuichiro Ando, Weiler, Mathias, Huebl, Hans, Teruya Shinjo, Goennenwein, Sebastian T. B., and Masashi Shiraishi
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METAL oxide semiconductor field-effect transistors ,SPINTRONICS ,DAMPING (Mechanics) ,SEMICONDUCTOR doping ,FERROMAGNETIC resonance - Abstract
We studied the spin injection in a NiFe(Py)/Si system using broadband ferromagnetic resonance spectroscopy. The Gilbert damping parameter of the Py layer on top of the Si channel was determined as a function of the Si doping concentration and Py layer thickness. For a fixed Py thickness, we observed an increase in the Gilbert damping parameter with decreasing resistivity of the Si channel. For a fixed Si doping concentration, we measured an increasing Gilbert damping parameter for decreasing Py layer thickness. No increase in the Gilbert damping parameter was found for Py/Si samples with an insulating interlayer. We attribute our observations to an enhanced spin injection into the low-resistivity Si by spin pumping. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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17. Magnon-based logic in a multi-terminal YIG/Pt nanostructure.
- Author
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Ganzhorn, Kathrin, Klingler, Stefan, Wimmer, Tobias, Geprägs, Stephan, Gross, Rudolf, Huebl, Hans, and Goennenwein, Sebastian T. B.
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MAGNONS ,NANOSTRUCTURED materials ,YTTRIUM iron garnet ,BOOLEAN searching ,ELECTRONIC information resources - Abstract
Boolean logic is the foundation of modern digital information processing. Recently, there has been a growing interest in phenomena based on pure spin currents, which allows to move from charge to spin based logic gates. We study a proof-of-principle logic device based on the ferrimagnetic insulator Yttrium Iron Garnet, with Pt strips acting as injectors and detectors for non-equilibrium magnons. We experimentally observe incoherent superposition of magnons generated by different injectors. This allows to implement a fully functional majority gate, enabling multiple logic operations (AND and OR) in one and the same device. Clocking frequencies of the order of several GHz and straightforward down-scaling make our device promising for applications. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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18. Non-local magnetoresistance in YIG/Pt nanostructures.
- Author
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Goennenwein, Sebastian T. B., Schlitz, Richard, Pernpeintner, Matthias, Ganzhorn, Kathrin, Althammer, Matthias, Gross, Rudolf, and Huebl, Hans
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MAGNETORESISTANCE ,NANOSTRUCTURED materials ,YTTRIUM iron garnet ,MAGNETORESISTIVE devices ,SPIN Hall effect - Abstract
We study the local and non-local magnetoresistance of thin Pt strips deposited onto yttrium iron garnet. The local magnetoresistive response, inferred from the voltage drop measured along one given Pt strip upon current-biasing it, shows the characteristic magnetization orientation dependence of the spin Hall magnetoresistance. We simultaneously also record the non-local voltage appearing along a second, electrically isolated, Pt strip, separated from the current carrying one by a gap of a few 100nm. The corresponding non-local magnetoresistance exhibits the symmetry expected for a magnon spin accumulation-driven process, confirming the results recently put forward by Cornelissen et al. ["Long-distance transport of magnon spin information in a magnetic insulator at room temperature," Nat. Phys. (published online 14 September 2015)]. Our magnetotransport data, taken at a series of different temperatures as a function of magnetic field orientation, rotating the externally applied field in three mutually orthogonal planes, show that the mechanisms behind the spin Hall and the non-local magnetoresistance are qualitatively different. In particular, the non-local magnetoresistance vanishes at liquid Helium temperatures, while the spin Hall magnetoresistance prevails. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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19. High cooperativity coupling between a phosphorus donor spin ensemble and a superconducting microwave resonator.
- Author
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Zollitsch, Christoph W., Mueller, Kai, Franke, David P., Goennenwein, Sebastian T. B., Brandt, Martin S., Gross, Rudolf, and Huebl, Hans
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PHOSPHORUS ,COUPLING reactions (Chemistry) ,SUPERCONDUCTING resonators ,SILICON ,CRYSTAL lattices ,TEMPERATURE effect - Abstract
We investigate the coupling of an ensemble of phosphorus donors in an isotopically purified
28 Si host lattice interacting with a superconducting coplanar waveguide resonator. The microwave transmission spectrum of the resonator shows a normal mode splitting characteristic for high cooperativity. The evaluated collective coupling strength geff is of the same order as the loss rate of the spin system γ, indicating the onset of strong coupling. We develop a statistical model to describe the influence of temperature on the coupling strength from 50mK to 3:5K and find a scaling of the coupling strength with the square root of the number of thermally polarized spins. [ABSTRACT FROM AUTHOR]- Published
- 2015
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20. Note: Derivative divide, a method for the analysis of broadband ferromagnetic resonance in the frequency domain.
- Author
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Maier-Flaig, Hannes, Goennenwein, Sebastian T. B., Ohshima, Ryo, Shiraishi, Masashi, Gross, Rudolf, Huebl, Hans, and Weiler, Mathias
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FERROMAGNETIC resonance ,MAGNETIC properties ,FREQUENCY spectra ,MAGNETIC fields ,COPLANAR waveguides - Abstract
Broadband ferromagnetic resonance (bbFMR) spectroscopy is an established experimental tool to quantify magnetic properties. Due to frequency-dependent transmission of the microwave setup, bbFMR measurements in the frequency domain require a suitable background removal method. Here, we present a measurement and data analysis protocol that allows us to perform quantitative frequency-swept bbFMR measurements without the need for a calibration of the microwave setup. We furthermore compare the results of the proposed frequency space analysis and a conventional analysis in field-space of bbFMR data obtained from a permalloy thin film. The very good agreement of the extracted parameters using the two methods shows the reliability of our method. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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21. Anomalous Hall effect in YIG|Pt bilayers.
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Meyer, Sibylle, Schlitz, Richard, Geprägs, Stephan, Opel, Matthias, Huebl, Hans, Gross, Rudolf, and Goennenwein, Sebastian T. B.
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HALL effect ,YTTRIUM compounds ,MAGNETIC properties of metals ,MAGNETORESISTANCE ,FERRIMAGNETISM ,METALS at low temperatures - Abstract
We measure the ordinary and the anomalous Hall effect in a set of yttrium iron garnetjplatinum (YIGjPt) bilayers via magnetization orientation dependent magnetoresistance experiments. Our data show that the presence of the ferrimagnetic insulator YIG leads to an anomalous Hall effect like voltage in Pt, which is sensitive to both Pt thickness and temperature. Interpretation of the experimental findings in terms of the spin Hall anomalous Hall effect indicates that the imaginary part of the spin mixing conductance G
i plays a crucial role in YIG|Pt bilayers. In particular, our data suggest a sign change in Gi between 10K and 300 K. Additionally, we report a higher order Hall effect contribution, which appears in thin Pt films on YIG at low temperatures. [ABSTRACT FROM AUTHOR]- Published
- 2015
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22. Ultrafast electronic readout of diamond nitrogen-vacancy centres coupled to graphene.
- Author
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Brenneis, Andreas, Gaudreau, Louis, Seifert, Max, Karl, Helmut, Brandt, Martin S., Huebl, Hans, Garrido, Jose A., Koppens, Frank H. L., and Holleitner, Alexander W.
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DIAMONDS ,VACANCIES in crystals ,GRAPHENE ,NITROGEN ,ENERGY transfer ,ELECTRON spin - Abstract
Non-radiative transfer processes are often regarded as loss channels for an optical emitter because they are inherently difficult to access experimentally. Recently, it has been shown that emitters, such as fluorophores and nitrogen-vacancy centres in diamond, can exhibit a strong non-radiative energy transfer to graphene. So far, the energy of the transferred electronic excitations has been considered to be lost within the electron bath of the graphene. Here we demonstrate that the transferred excitations can be read out by detecting corresponding currents with a picosecond time resolution. We detect electronically the spin of nitrogen-vacancy centres in diamond and control the non-radiative transfer to graphene by electron spin resonance. Our results open the avenue for incorporating nitrogen-vacancy centres into ultrafast electronic circuits and for harvesting non-radiative transfer processes electronically. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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23. Spin Hall magnetoimpedance.
- Author
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Lotze, Johannes, Huebl, Hans, Gross, Rudolf, and Goennenwein, Sebastian T. B.
- Subjects
- *
SPIN Hall effect , *MAGNETORESISTANCE , *ELECTRICAL resistance tomography , *ELECTRIC insulators & insulation , *FERRIMAGNETIC materials - Abstract
The recently discovered spin Hall magnetoresistance effect electrically probes pure spin current flow across a ferrimagnetic insulator/normal metal bilayer interface. While usually the dc electrical resistance of the bilayer is measured as a function of the magnetization orientation in the magnetic insulator, here we present magnetoimpedance measurements using bias currents with frequencies up to several GHz. We find that the spin Hall magnetoresistance effect is frequency independent up tofrequencies of 3 GHz, corroborating the assumption of a frequency-independent spin Hall angle. Our data therefore show that all interaction time constants relevant for the spin Hall magnetoresistance effect are shorter than about 50 ps. Therefore this technique should allow for the fast readout of the magnetization direction in magnetic insulator/normal metal bilayers. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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24. Determination of effective mechanical properties of a double-layer beam by means of a nano-electromechanical transducer.
- Author
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Hocke, Fredrik, Pernpeintner, Matthias, Xiaoqing Zhou, Schliesser, Albert, Kippenberg, Tobias J., Huebl, Hans, and Gross, Rudolf
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NANOPARTICLES ,ELECTROMECHANICAL devices ,LASER beams ,MECHANICAL behavior of materials ,SILICON nitride ,MULTIFERROIC materials - Abstract
We investigate the mechanical properties of a doubly clamped' double-layer nanobeam embedded into an electromechanical system. The nanobeam consists of a highly pre-stressed silicon nitride and a superconducting niobium layer. By measuring the mechanical displacement spectral density both in the linear and the nonlinear Duffing regime, we determine the pre-stress and the effective Young's modulus of the nanobeam. An analytical double-layer model quantitatively corroborates the measured values. This suggests that this model can be used to design mechanical multilayer systems for electro- and optomechanical devices, including materials controllable by external parameters such as piezoelectric, magnetostrictive, or in more general multiferroic materials. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
25. Circuit-quantum electrodynamics with direct magnetic coupling to single-atom spin qubits in isotopically enriched 28Si.
- Author
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Tosi, Guilherme, Mohiyaddin, Fahd A., Huebl, Hans, and Morello, Andrea
- Subjects
QUANTUM electrodynamics ,NANOFABRICATION ,MAGNETIC coupling ,RESONATORS ,MAGNETIC fields - Abstract
Recent advances in silicon nanofabrication have allowed the manipulation of spin qubits that are extremely isolated from noise sources, being therefore the semiconductor equivalent of single atoms in vacuum. We investigate the possibility of directly coupling an electron spin qubit to a superconducting resonator magnetic vacuum field. By using resonators modified to increase the vacuum magnetic field at the qubit location, and isotopically purified
28 Si substrates, it is possible to achieve coupling rates faster than the single spin dephasing. This opens up new avenues for circuitquantum electrodynamics with spins, and provides a pathway for dispersive read-out of spin qubits via superconducting resonators. [ABSTRACT FROM AUTHOR]- Published
- 2014
- Full Text
- View/download PDF
26. Time resolved spin Seebeck effect experiments.
- Author
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Roschewsky, Niklas, Schreier, Michael, Kamra, Akashdeep, Schade, Felix, Ganzhorn, Kathrin, Meyer, Sibylle, Huebl, Hans, Geprägs, Stephan, Gross, Rudolf, and Goennenwein, Sebastian T. B.
- Subjects
SEEBECK effect ,TRANSIENT analysis ,THERMOELECTRIC power ,PLATINUM ,YTTRIUM iron garnet ,MAGNONS - Abstract
In this Letter, we present the results of transient thermopower experiments, performed at room temperature on yttrium iron garnet/platinum bilayers. Upon application of a time-varying thermal gradient, we observe a characteristic low-pass frequency response of the ensuing thermopower voltage with cutoff frequencies of up to 37 MHz. We interpret our results in terms of the spin Seebeck effect, and argue that small wavevector magnons are of minor importance for the spin Seebeck effect in our thin film hybrid structures. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
27. Current heating induced spin Seebeck effect.
- Author
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Schreier, Michael, Roschewsky, Niklas, Dobler, Erich, Meyer, Sibylle, Huebl, Hans, Gross, Rudolf, and Goennenwein, Sebastian T. B.
- Subjects
SEEBECK effect ,THERMOELECTRICITY ,MAGNETIC fields ,ELECTRIC potential ,ELECTRIC heating elements - Abstract
A measurement technique for the spin Seebeck effect is presented, wherein the normal metal layer used for its detection is exploited simultaneously as a resistive heater and thermometer. We show how the various contributions to the measured total signal can be disentangled, allowing to extract the voltage signal solely caused by the spin Seebeck effect. To this end, we performed measurements as a function of the external magnetic field strength and its orientation. We find that the effect scales linearly with the induced rise in temperature, as expected for the spin Seebeck effect. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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- View/download PDF
28. The electrically detected magnetic resonance microscope: Combining conductive atomic force microscopy with electrically detected magnetic resonance.
- Author
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Klein, Konrad, Hauer, Benedikt, Stoib, Benedikt, Trautwein, Markus, Matich, Sonja, Huebl, Hans, Astakhov, Oleksandr, Finger, Friedhelm, Bittl, Robert, Stutzmann, Martin, and Brandt, Martin S.
- Subjects
SCANNING probe microscopy ,MAGNETIC resonance ,ATOMIC force microscopy ,ELECTRIC currents ,AMORPHOUS substances ,SILICON research - Abstract
We present the design and implementation of a scanning probe microscope, which combines electrically detected magnetic resonance (EDMR) and (photo-)conductive atomic force microscopy ((p)cAFM). The integration of a 3-loop 2-gap X-band microwave resonator into an AFM allows the use of conductive AFM tips as a movable contact for EDMR experiments. The optical readout of the AFM cantilever is based on an infrared laser to avoid disturbances of current measurements by absorption of straylight of the detection laser. Using amorphous silicon thin film samples with varying defect densities, the capability to detect a spatial EDMR contrast is demonstrated. Resonant current changes as low as 20 fA can be detected, allowing the method to realize a spin sensitivity of [formula] at room temperature. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
29. Electrically detected double electron–electron resonance: exchange interaction of P donors and P defects at the Si/SiO interface.
- Author
-
Suckert, Max, Hoehne, Felix, Dreher, Lukas, Kuenzl, Markus, Huebl, Hans, Stutzmann, Martin, and Brandt, Martin S.
- Subjects
ELECTRON-electron interactions ,EXCHANGE interactions (Magnetism) ,PROTONS ,SILICON oxide ,EPITAXY ,COMPUTER simulation - Abstract
We study the coupling of Pdangling bond defects at the Si/SiO2interface and31P donors in an epitaxial layer directly underneath using electrically detected double electron–electron resonance (EDDEER). An exponential decay of the EDDEER signal is observed, which is attributed to a broad distribution of exchange coupling strengthsJ/2π from 25 kHz to 3 MHz. Comparison of the experimental data with a numerical simulation of the exchange coupling shows that this range of coupling strengths corresponds to31P–Pdistances ranging from 14 nm to 20 nm. [ABSTRACT FROM PUBLISHER]
- Published
- 2013
- Full Text
- View/download PDF
30. High Cooperativity in Coupled Microwave Resonator Ferrimagnetic Insulator Hybrids.
- Author
-
Huebl, Hans, Zollitsch, Christoph W., Lotze, Johannes, Hocke, Fredrik, Greifenstein, Moritz, Marx, Achim, Gross, Rudolf, and Goennenwein, Sebastian T. B.
- Subjects
- *
FERRIMAGNETIC materials , *COUPLING constants , *NUCLEAR spin , *GALLIUM , *YTTRIUM iron garnet , *SQUARE root , *QUANTUM electrodynamics - Abstract
We report the observation of strong coupling between the exchange-coupled spins in a gallium-doped yttrium iron garnet and a superconducting coplanar microwave resonator made from Nb. The measured coupling rate of 450 MHz is proportional to the square root of the number of exchange-coupled spins and well exceeds the loss rate of 50 MHz of the spin system. This demonstrates that exchange-coupled systems are suitable for cavity quantum electrodynamics experiments, while allowing high integration densities due to their spin densities of the order of one Bohr magneton per atom. Our results furthermore show, that experiments with multiple exchange-coupled spin systems interacting via a single resonator are within reach. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
31. Electromechanically induced absorption in a circuit nano-electromechanical system.
- Author
-
Hocke, Fredrik, Xiaoqing Zhou, Schliesser, Albert, Kippenberg, Tobias J., Huebl, Hans, and Gross, Rudolf
- Subjects
ELECTROMECHANICAL devices ,HYBRID systems ,RESONATORS ,NANOELECTROMECHANICAL systems ,SPECTRUM analysis - Abstract
A detailed analysis of electromechanically induced absorption (EMIA) in a circuit nano-electromechanical hybrid system consisting of a superconducting microwave resonator coupled to a nanomechanical beam is presented. By performing two-tone spectroscopy experiments, we have studied EMIA as a function of the drive power over a wide range of drive and probe tone detunings. We found good quantitative agreement between experiment and theoretical modeling based on the Hamiltonian formulation of a generic electromechanical system. We show that the absorption of microwave signals in an extremely narrow frequency band (Δω/2π Hz) around the cavity resonance of about 6 GHz can be adjusted over a range of more than 25 dB on varying the drive tone power by a factor of 2. Possible applications of this phenomenon include notch filters to cut out extremely narrow frequency bands (
- Published
- 2012
- Full Text
- View/download PDF
32. Electrical detection of coherent 31P spin quantum states.
- Author
-
Stegner, Andre R., Boehme, Christoph, Huebl, Hans, Stutzmann, Martin, Lips, Klaus, and Brandt, Martin S.
- Subjects
QUANTUM dots ,MAGNETIC resonance ,ELECTRON paramagnetic resonance ,MICROELECTRONICS research ,INTERFACES (Physical sciences) ,ION recombination ,QUANTUM tunneling - Abstract
In recent years, a variety of solid-state qubits has been realized, including quantum dots, superconducting tunnel junctions and point defects. Owing to its potential compatibility with existing microelectronics, the proposal by Kane—on the basis of phosphorus donors in silicon—has been pursued intensively. A key issue of this concept is the readout of the 31P quantum state. Electrical measurements of magnetic resonance have been carried out on single spins, but the statistical nature of these experiments based on random-telegraph-noise measurements has impeded the readout of single spin states. Here, we demonstrate the measurement of the spin state of 31P donor electrons in silicon and the observation of Rabi flops by purely electric means, that is by coherent manipulation of spin-dependent charge-carrier recombination between the 31P donor and paramagnetic localized states at the Si/SiO2 interface. The electron spin information is shown to be coupled through the hyperfine interaction to the 31P nucleus, suggesting that recombination-based readout of nuclear spins is feasible. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
33. Origin of the spin Seebeck effect in compensated ferrimagnets.
- Author
-
Geprägs, Stephan, Kehlberger, Andreas, Coletta, Francesco Della, Qiu, Zhiyong, Guo, Er-Jia, Schulz, Tomek, Mix, Christian, Meyer, Sibylle, Kamra, Akashdeep, Althammer, Matthias, Huebl, Hans, Jakob, Gerhard, Ohnuma, Yuichi, Adachi, Hiroto, Barker, Joseph, Maekawa, Sadamichi, Bauer, Gerrit E. W., Saitoh, Eiji, Gross, Rudolf, and Goennenwein, Sebastian T. B.
- Published
- 2016
- Full Text
- View/download PDF
34. Lock-in detection for pulsed electrically detected magnetic resonance.
- Author
-
Hoehne, Felix, Dreher, Lukas, Behrends, Jan, Fehr, Matthias, Huebl, Hans, Lips, Klaus, Schnegg, Alexander, Suckert, Max, Stutzmann, Martin, and Brandt, Martin S.
- Subjects
MAGNETIC resonance ,MAGNETIC resonance imaging ,NOISE ,PHOSPHORUS ,SILICON - Abstract
We show that in pulsed electrically detected magnetic resonance (pEDMR) signal modulation in combination with a lock-in detection scheme can reduce the low-frequency noise level by one order of magnitude and in addition removes the microwave-induced non-resonant background. This is exemplarily demonstrated for spin-echo measurements in phosphorus-doped silicon. The modulation of the signal is achieved by cycling the phase of the projection pulse used in pEDMR for the readout of the spin state. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
35. Hydrogen and Magnetism in Ga1-xMnxAs.
- Author
-
Goennenwein, Sebastian T. B., Wassner, Thomas A., Huebl, Hans, Koeder, Achim, Schoch, Wladimir, Waag, Andreas, Philipp, Jan B., Opel, Matthias, Gross, Rudolf, Stutzmann, Martin, and et al., et al.
- Published
- 2006
- Full Text
- View/download PDF
36. Exchange magnon-polaritons in microwave cavities.
- Author
-
Yunshan Cao, Peng Yan, Huebl, Hans, Goennenwein, Sebastian T. B., and Bauer, Gerrit E. W.
- Subjects
- *
MAGNETIC films , *FERROMAGNETIC resonance , *FERROMAGNETISM , *SPIN waves , *CAVITY polaritons , *MAGNONS - Abstract
We formulate a scattering theory to study magnetic films in microwave cavities beyond the independent-spin and rotating-wave approximations of the Tavis-Cummings model. We demonstrate that strong coupling can be realized not only for the ferromagnetic resonance mode, but alsofor spin-wave resonances; the coupling strengths are mode dependent and decrease with increasing mode index. The strong-coupling regime can also be accessed electrically by spin pumping into a metal contact. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
37. Theoretical model for torque differential magnetometry of single-domain magnets.
- Author
-
Kamra, Akashdeep, Schreier, Michael, Huebl, Hans, and Goennenwein, Sebastian T. B.
- Subjects
- *
MAGNETOMETERS , *MAGNETIC properties , *MECHANICAL oscillations , *FREE energy (Thermodynamics) , *TORQUE control - Abstract
We present a generic theoretical model for torque differential magnetometry (TDM)-an experimental method for determining the magnetic properties of a magnetic specimen by recording the resonance frequency of a mechanical oscillator, on which the magnetic specimen has been mounted, as a function of the applied magnetic field. The effective stiffness change, and hence the resonance frequency shift, of the oscillator due to the magnetic torque on the specimen is calculated, treating the magnetic specimen as a single magnetic domain. Our model can deal with an arbitrary magnetic free-energy density characterizing the specimen, as well as any relative orientation of the applied magnetic field, the specimen, and the oscillator. Our calculations agree well with published experimental data. The theoretical model presented here allows one to take full advantage of TDM as an efficient magnetometry method. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
38. Spin Seebeck effect at microwave frequencies.
- Author
-
Schreier, Michael, Kramer, Franz, Huebl, Hans, Geprägs, Stephan, Gross, Rudolf, Goennenwein, Sebastian T. B., Noack, Timo, Langner, Thomas, Serga, Alexander A., Hillebrands, Burkard, and Vasyuchka, Vitaliy I.
- Subjects
- *
SEEBECK effect , *YTTRIUM iron garnet , *FERROMAGNETISM - Abstract
We experimentally study the transient voltage response of yttrium iron garnet/platinum bilayer samples subject to periodic heating up to gigahertz frequencies. We observe an intrinsic cutoff frequency of the induced thermopower voltage, which characteristically depends on the thickness of the yttrium iron garnet film. The cutoff frequency reaches values of up to 350 MHz in a 50-nm-thick yttrium iron garnet film, but drops to below 1 MHz for several-micrometer-thick films. These data corroborate the notion that the magnon spectrum responsible for the spin current emission in the spin Seebeck effect can be shaped by tuning the thickness of the ferromagnetic layer. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
39. Quantum State Engineering with Circuit Electromechanical Three-Body Interactions.
- Author
-
Abdi, Mehdi, Pempeintner, Matthias, Gross, Rudolf, Huebl, Hans, and Hartmann, Michael J.
- Subjects
- *
HYBRID systems , *QUANTUM states , *PHOTONS , *PHONONS , *QUANTUM electrodynamics , *SUPERCONDUCTING microwave devices , *POLARITONS - Abstract
We propose a hybrid system with quantum mechanical three-body interactions between photons, phonons, and qubit excitations. These interactions take place in a circuit quantum electrodynamical architecture with a superconducting microwave resonator coupled to a transmon qubit whose shunt capacitance is free to mechanically oscillate. We show that this system design features a three-mode polariton-mechanical mode and a nonlinear transmon-mechanical mode interaction in the strong coupling regime. Together with the strong resonator-transmon interaction, these properties provide intriguing opportunities for manipulations of this hybrid quantum system. We show, in particular, the feasibility of cooling the mechanical motion down to its ground state and preparing various nonclassical states including mechanical Fock and cat states and hybrid tripartite entangled states. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
40. Spin Hall noise.
- Author
-
Kamra, Akashdeep, Witek, Friedrich P., Meyer, Sibylle, Huebl, Hans, Geprägs, Stephan, Gross, Rudolf, Bauer, Gerrit E. W., and Goennenwein, Sebastian T. B.
- Subjects
- *
SPIN Hall effect , *YTTRIUM iron garnet , *NOISE , *MAGNETIZATION , *MAGNETORESISTANCE , *FLUCTUATION-dissipation relationships (Physics) - Abstract
We measure the low-frequency thermal fluctuations of pure spin current in a platinum film deposited on yttrium iron garnet via the inverse spin Hall effect (ISHE)-mediated voltage noise as a function of the angle a between the magnetization and the transport direction. The results are consistent with the fluctuation-dissipation theorem in terms of the recently discovered spin Hall magnetoresistance (SMR). We present a microscopic description of the α dependence of the voltage noise in terms of spin-current fluctuations and ISHE. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
41. Real-time electrical detection of coherent spin oscillations.
- Author
-
Hoehne, Felix, Huck, Christian, Brandt, Martin S., and Huebl, Hans
- Subjects
- *
BANDWIDTHS , *MAGNETIC resonance , *SPIN-density functional theory , *SEMICONDUCTORS , *COMPUTER simulation - Abstract
We demonstrate that the bandwidth of pulsed electrically detected magnetic resonance can be increased to at least 80 MHz using a radio-frequency-reflectometry detection scheme. Using this technique, we measure coherent spin oscillations in real time during a resonant microwave pulse. We find that the observed signal is in quantitative agreement with simulations based on rate equations modeling the recombination dynamics of the spin system under study. The increased bandwidth opens the way to electrically study faster spin-dependent recombination processes, e.g., in direct semiconductors which so far have almost exclusively been studied by optically detected magnetic resonance. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
42. Experimental Test of the Spin Mixing Interface Conductivity Concept.
- Author
-
Weiler, Mathias, Althammer, Matthias, Schreier, Michael, Lotze, Johannes, Pernpeintner, Matthias, Meyer, Sibylle, Huebl, Hans, Gross, Rudolf, Kamra, Akashdeep, Jiang Xiao, Yan-Ting Chen, HuJun Jiao, Bauer, Gerrit E. W., and Goennenwein, Sebastian T. B.
- Subjects
- *
MAGNETORESISTANCE , *HALL effect , *NUCLEAR spin , *THERMAL conductivity , *YTTRIUM iron garnet - Abstract
We perform a quantitative, comparative study of the spin pumping, spin Seebeck, and spin Hall magnetoresistance effects, all detected via the inverse spin Hall effect in a series of over 20 yttrium iron garnet/Pt samples. Our experimental results fully support present, exclusively spin current-based, theoretical models using a single set of plausible parameters for spin mixing conductance, spin Hall angle, and spin diffusion length. Our findings establish the purely spintronic nature of the aforementioned effects and provide a quantitative description, in particular, of the spin Seebeck effect. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
43. Quantitative study of the spin Hall magnetoresistance in ferromagnetic insulator/normal metal hybrids.
- Author
-
Althammer, Matthias, Meyer, Sibylle, Hiroyasu Nakayama, Schreier, Michael, Altmannshofer, Stephan, Weiler, Mathias, Huebl, Hans, Geprägs, Stephan, Opel, Matthias, Gross, Rudolf, Meier, Daniel, Klewe, Christoph, Kuschel, Timo, Schmalhorst, Jan-Michael, Reiss, Günter, Shen, Liming, Gupta, Arunava, Chen, Yan-Ting, Gerrit E. W. Bauer, and Eiji Saitoh
- Subjects
- *
GALVANOMAGNETIC effects , *ELECTRIC resistance , *MAGNETIC fields , *SOLID solutions , *FERRITES - Abstract
We experimentally investigate and quantitatively analyze the spin Hall magnetoresistance effect in ferromagnetic insulator/platinum and ferromagnetic insulator/nonferromagnetic metal/platinum hybrid structures. For the ferromagnetic insulator, we use either yttrium iron garnet, nickel ferrite, or magnetite and for the nonferromagnet, copper or gold. The spin Hall magnetoresistance effect is theoretically ascribed to the combined action of spin Hall and inverse spin Hall effect in the platinum metal top layer. It therefore should characteristically depend upon the orientation of the magnetization in the adjacent ferromagnet and prevail even if an additional, nonferromagnetic metal layer is inserted between Pt and the ferromagnet. Our experimental data corroborate these theoretical conjectures. Using the spin Hall magnetoresistance theory to analyze our data, we extract the spin Hall angle and the spin diffusion length in platinum. For a spin-mixing conductance of 4 × 1014 Ω-1m-2, we obtain a spin Hall angle of 0.11 ± 0.08 and a spin diffusion length of (1.5 ± 0.5) nm for Pt in our thin-film samples. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
44. Local Charge and Spin Currents in Magnetothermal Landscapes.
- Author
-
Weiler, Mathias, Althammer, Matthias, Czeschka, Franz D., Huebl, Hans, Wagner, Martin S., Opel, Matthias, Imort, Inga-Mareen, Reiss, Günter, Thomas, Andy, Gross, Rudolf, and Goennenwein, Sebastian T. B.
- Subjects
- *
FERROMAGNETIC materials , *THIN films , *THERMAL insulation , *ELECTRIC potential , *LASER beams , *COBALT compounds - Abstract
A scannable laser beam is used to generate local thermal gradients in metallic (Co2FeAl) or insulating (Y3Fe5012) ferromagnetic thin films. We study the resulting local charge and spin currents that arise due to the anomalous Nernst effect (ANE) and the spin Seebeck effect (SSE), respectively. In the local ANE experiments, we detect the voltage in the Co2FeAl thin film plane as a function of the laser-spot position and external magnetic field magnitude and orientation. The local SSE effect is detected in a similar fashion by exploiting the inverse spin Hall effect in a Pt layer deposited on top of the Y3Fe5012. Our findings establish local thermal spin and charge current generation as well as spin caloritronic domain imaging. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
45. High-resolution electrical detection of free induction decay and Hahn echoes in phosphorus-doped silicon.
- Author
-
Jinming Lu, Hoehne, Felix, Stegner, Andre R., Dreher, Lukas, Stutzmann, Martin, Brandt, Martin S., and Huebl, Hans
- Subjects
- *
SILICON isotopes , *ELECTRIC properties of silicon , *SEMICONDUCTOR doping , *ELECTRON paramagnetic resonance , *MAGNETIC resonance , *RADIOACTIVE decay , *SPECTRUM analysis - Abstract
Paramagnetic centers in a solid-state environment usually give rise to inhomogeneously broadened electron paramagnetic resonance (EPR) lines, making conventionally detected free induction decay (FID) signals disappear within the spectrometer dead time. Here, high-resolution experimental results of an electrically detected FID of phosphorus donors in silicon epilayers with natural isotope composition are presented, showing Ramsey fringes within the first 150 ns. An analytical model is developed to account for the data obtained as well as for the results of analogous two-pulse echo experiments. The results of a numerical calculation are further presented to assess the capability of the method to study the exchange interaction between the donor spins and paramagnetic interface defect states. In the current samples, an upper limit of 5 MHz is obtained for the average exchange interaction. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
46. Echo Trains in Pulsed Electron Spin Resonance of a Strongly Coupled Spin Ensemble.
- Author
-
Weichselbaumer, Stefan, Zens, Matthias, Zollitsch, Christoph W., Brandt, Martin S., Rotter, Stefan, Gross, Rudolf, and Huebl, Hans
- Subjects
- *
ELECTRON paramagnetic resonance , *LUMPED elements , *ECHO , *SPIN labels , *NUMERICAL calculations - Abstract
We report on a novel dynamical phenomenon in electron spin resonance experiments of phosphorus donors. When strongly coupling the paramagnetic ensemble to a superconducting lumped element resonator, the coherent exchange between these two subsystems leads to a train of periodic, self-stimulated echoes after a conventional Hahn echo pulse sequence. The presence of these multiecho signatures is explained using a simple model based on spins rotating on the Bloch sphere, backed up by numerical calculations using the inhomogeneous Tavis-Cummings Hamiltonian. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
47. Exchange-Enhanced Ultrastrong Magnon-Magnon Coupling in a Compensated Ferrimagnet.
- Author
-
Liensberger, Lukas, Kamra, Akashdeep, Maier-Flaig, Hannes, Geprägs, Stephan, Erb, Andreas, Goennenwein, Sebastian T. B., Gross, Rudolf, Belzig, Wolfgang, Huebl, Hans, and Weiler, Mathias
- Subjects
- *
MAGNONS , *FERRIMAGNETIC materials , *MAGNETIC anisotropy , *FERROMAGNETIC resonance , *ROTATIONAL symmetry , *SYMMETRY breaking , *SINGLE crystals - Abstract
We experimentally study the spin dynamics in a gadolinium iron garnet single crystal using broadband ferromagnetic resonance. Close to the ferrimagnetic compensation temperature, we observe ultrastrong coupling of clockwise and counterclockwise magnon modes. The magnon-magnon coupling strength reaches almost 40% of the mode frequency and can be tuned by varying the direction of the external magnetic field. We theoretically explain the observed mode coupling as arising from the broken rotational symmetry due to a weak magnetocrystalline anisotropy. The effect of this anisotropy is exchange enhanced around the ferrimagnetic compensation point. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
48. Spin-Torque Excitation of Perpendicular Standing Spin Waves in Coupled YIG/Co Heterostructures.
- Author
-
Klingler, Stefan, Amin, Vivek, Geprägs, Stephan, Ganzhorn, Kathrin, Maier-Flaig, Hannes, Althammer, Matthias, Huebl, Hans, Gross, Rudolf, McMichael, Robert D., Stiles, Mark D., Goennenwein, Sebastian T. B., and Weiler, Mathias
- Subjects
- *
SPIN waves , *FERROMAGNETIC resonance , *STANDING waves - Abstract
We investigate yttrium iron garnet (YIG)/cobalt (Co) heterostructures using broadband ferromagnetic resonance (FMR). We observe an efficient excitation of perpendicular standing spin waves (PSSWs) in the YIG layer when the resonance frequencies of the YIG PSSWs and the Co FMR line coincide. Avoided crossings of YIG PSSWs and the Co FMR line are found and modeled using mutual spin pumping and exchange torques. The excitation of PSSWs is suppressed by a thin aluminum oxide interlayer but persists with a copper interlayer, in agreement with the proposed model. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
49. Helimagnon Resonances in an Intrinsic Chiral Magnonic Crystal.
- Author
-
Weiler, Mathias, Aqeel, Aisha, Mostovoy, Maxim, Leonov, Andrey, Geprägs, Stephan, Gross, Rudolf, Huebl, Hans, Palstra, Thomas T. M., and Goennenwein, Sebastian T. B.
- Subjects
- *
MAGNETIC resonance , *MAGNONS , *MAGNETIC insulators - Abstract
We experimentally study magnetic resonances in the helical and conical magnetic phases of the chiral magnetic insulator Cu2OSeO3 at the temperature T=5 K. Using a broadband microwave spectroscopy technique based on vector network analysis, we identify three distinct sets of helimagnon resonances in the frequency range 2 GHz≤f≤20 GHz with low magnetic damping α≤0.003. The extracted resonance frequencies are in accordance with calculations of the helimagnon band structure found in an intrinsic chiral magnonic crystal. The periodic modulation of the equilibrium spin direction that leads to the formation of the magnonic crystal is a direct consequence of the chiral magnetic ordering caused by the Dzyaloshinskii-Moriya interaction. The mode coupling in the magnonic crystal allows excitation of helimagnons with wave vectors that are multiples of the spiral wave vector. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
50. Spin Hall magnetoresistance in a canted ferrimagnet.
- Author
-
Ganzhorn, Kathrin, Barker, Joseph, Schlitz, Richard, Piot, Benjamin A., Ollefs, Katharina, Guillou, Francois, Wilhelm, Fabrice, Rogalev, Andrei, Opel, Matthias, Althammer, Matthias, Geprägs, Stephan, Huebl, Hans, Gross, Rudolf, Bauer, Gerrit E. W., and Goennenwein, Sebastian T. B.
- Subjects
- *
SPIN Hall effect , *MAGNETORESISTANCE , *MAGNETIC transitions , *SUPERLATTICES , *X-ray absorption - Abstract
We study the spin Hall magnetoresistance effect in ferrimagnet/normal metal bilayers, comparing the response in collinear and canted magnetic phases. In the collinear magnetic phase, in which the sublattice magnetic moments are all aligned along the same axis, we observe the conventional spin Hall magnetoresistance. In contrast, in the canted phase, the magnetoresistance changes sign. Using atomistic spin simulations and x-ray absorption experiments, we can understand these observations in terms of the magnetic field and temperature dependent orientation of magnetic moments on different magnetic sublattices. This enables a magnetotransport based investigation of noncollinear magnetic textures. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
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