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356 results on '"RØnnow, Henrik M."'

102. Randomness and frustration in a S= 12 square-lattice Heisenberg antiferromagnet

Author

Fogh, Ellen, Mustonen, Otto, Babkevich, Peter, Katukuri, Vamshi M., Walker, Helen C., Mangin-Thro, Lucile, Karppinen, Maarit, Ward, Simon, Normand, Bruce, Rønnow, Henrik M., Swiss Federal Institute of Technology Lausanne, University of Sheffield, Max Planck Institute for Solid State Research, Rutherford Appleton Laboratory, Institut Laue-Langevin, Department of Chemistry and Materials Science, European Spallation Source, Aalto-yliopisto, and Aalto University

Abstract

Funding Information: We thank E. Cussen, A. Sandvik, and O. Yazyev for helpful discussions. This work was funded by the Swiss National Science Foundation, including by its Sinergia networks MPBH (Grant Nos. CRSII2 141962/1 and CRSII2 160765/1) and Nanoskyrmionics (Grant No. 171003), by the European Research Council through the project CONQUEST (Grant No. 259602) and the Synergy network HERO (Grant No. 810451), and by the Leverhulme Trust through Research Project Grant No. RPG-2017-109 and Early Career Fellowship No. ECF-2021-170. We thank the ILL and ISIS for the allocation of beam time for this study. Data collected at both facilities are available as Refs. . Publisher Copyright: © 2022 American Physical Society. We explore the interplay between randomness and magnetic frustration in the series of S=12 Heisenberg square-lattice compounds Sr2CuTe1-xWxO6. Substituting W for Te alters the magnetic interactions dramatically, from strongly nearest-neighbor to next-nearest-neighbor antiferromagnetic coupling. We perform neutron scattering measurements to probe the magnetic ground state and excitations over a range of x. We propose a bond-disorder model that reproduces ground states with only short-ranged spin correlations in the mixed compounds. The calculated neutron diffraction patterns and powder spectra agree well with the measured data and allow detailed predictions for future measurements. We conclude that quenched randomness plays the major role in defining the physics of Sr2CuTe1-xWxO6 with frustration being less significant.

Published
2022

104. Dipolar Antiferromagnetism and Quantum Criticality in LiErF₄

Author

Kraemer, Conradin, Nikseresht, Neda, Piatek, Julian O., Tsyrulin, Nikolay, Piazza, Bastien Dalla, Kiefer, Klaus, Klemke, Bastian, Rosenbaum, Thomas F., Aeppli, Gabriel, Gannarelli, Ché, Prokes, Karel, Podlesnyak, Andrey, Strässle, Thierry, Keller, Lukas, Zaharko, Oksana, Krämer, Karl W., and Rønnow, Henrik M.

Published
2012
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106. Spin dynamics in the square-lattice cupola system Ba(TiO)Cu4(PO4)4

Author

Testa, Luc, primary, Babkevich, Peter, additional, Kato, Yasuyuki, additional, Kimura, Kenta, additional, Favre, Virgile, additional, Rodriguez-Rivera, Jose A., additional, Ollivier, Jacques, additional, Raymond, Stéphane, additional, Kimura, Tsuyoshi, additional, Motome, Yukitoshi, additional, Normand, Bruce, additional, and Rønnow, Henrik M., additional

Published
2022
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109. Influence of static correlation on the magnon dynamics of an itinerant ferromagnet with competing exchange interactions:First-principles study of MnBi

Author

Skovhus, Thorbjørn, Olsen, Thomas, Rønnow, Henrik M., Skovhus, Thorbjørn, Olsen, Thomas, and Rønnow, Henrik M.

Abstract

We present first-principles calculations of the dynamic susceptibility in strained and doped ferromagnetic MnBi using time-dependent density functional theory. In spite of being a metal, MnBi exhibits signatures of strong correlation and a proper description in the framework of density functional theory requires Hubbard corrections to the Mn d orbitals. To permit calculations of the dynamic susceptibility with Hubbard corrections applied to the ground-state electronic structure, we use a consistent rescaling of the exchange-correlation kernel maintaining the delicate balance between the magnon dispersion and the Stoner continuum. We find excellent agreement with the experimentally observed magnon dispersion for pristine MnBi and show that the material undergoes a phase transition to helical order under application of either doping or strain. The presented methodology paves the way for future linear response time-dependent density functional theory studies of magnetic phase transitions, also for the wide range of materials with pronounced static correlation effects that are not accounted for at the local density approximation level.

Published
2022

110. Magnetic structure of the topological semimetal Co3Sn2S2

Author

Soh, Jian-Rui, primary, Yi, ChangJiang, additional, Zivkovic, Ivica, additional, Qureshi, Navid, additional, Stunault, Anne, additional, Ouladdiaf, Bachir, additional, Rodríguez-Velamazán, J. Alberto, additional, Shi, YouGuo, additional, Rønnow, Henrik M., additional, and Boothroyd, Andrew T., additional

Published
2022
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112. The Magnetoelectric Effect in Lifepo4 -- Revisited

Author

Fogh, Ellen, primary, Klemke, Bastian, additional, Pages, Alexandre, additional, Li, Jiying, additional, Vaknin, David, additional, Rønnow, Henrik M., additional, Christensen, Niels B., additional, and Toft-Petersen, Rasmus, additional

Published
2022
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115. Magnetic Field Induced Quantum Spin Liquid in the Two Coupled Trillium Lattices of K2Ni2(SO4)3

Author

Živković, Ivica, primary, Favre, Virgile, additional, Salazar Mejia, Catalina, additional, Jeschke, Harald O., additional, Magrez, Arnaud, additional, Dabholkar, Bhupen, additional, Noculak, Vincent, additional, Freitas, Rafael S., additional, Jeong, Minki, additional, Hegde, Nagabhushan G., additional, Testa, Luc, additional, Babkevich, Peter, additional, Su, Yixi, additional, Manuel, Pascal, additional, Luetkens, Hubertus, additional, Baines, Christopher, additional, Baker, Peter J., additional, Wosnitza, Jochen, additional, Zaharko, Oksana, additional, Iqbal, Yasir, additional, Reuther, Johannes, additional, and Rønnow, Henrik M., additional

Published
2021
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118. Ferrimagnetic 120∘magnetic structure inCu2OSO4

Author

Favre, Virgile Yves, primary, Tucker, Gregory S., additional, Ritter, Clemens, additional, Sibille, Romain, additional, Manuel, Pascal, additional, Frontzek, Matthias D., additional, Kriener, Markus, additional, Yang, Lin, additional, Berger, Helmuth, additional, Magrez, Arnaud, additional, Casati, Nicola P. M., additional, Živković, Ivica, additional, and Rønnow, Henrik M., additional

Published
2020
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122. Persistent antiferromagnetic order in heavily overdoped Ca1-x La x FeAs2

Author

Martino, Edoardo, Bachmann, Maja D, Rossi, Lidia, Modic, Kimberly A, Zivkovic, Ivica, Rønnow, Henrik M, Moll, Philip J W, Akrap, Ana, Forró, László, and Katrych, Sergiy

Subjects
Condensed Matter::Superconductivity
Abstract

In the Ca1−x La x FeAs2 (1 1 2) family of pnictide superconductors, we have investigated a highly overdoped composition (x = 0.56), prepared by a high-pressure, high-temperature synthesis. Magnetic measurements show an antiferromagnetic transition at T N = 120 K, well above the one at lower doping (0.15

Published
2019

123. Magnetic Skyrmions: From Fundamental Physics to Topological Electronics

Author

White, Jonathan S., Grundler, Dirk, Raabe, Jörg, Rønnow, Henrik M., White, Jonathan S., Grundler, Dirk, Raabe, Jörg, and Rønnow, Henrik M.

Abstract

In Switzerland the National Science Foundation recently funded a network on Nano-Skyrmionics [https://skyrmions.epfl.ch] joining scientists from various institutions. Here, we provide a status report on selected forefront aspects of the research field. This includes identifying fundamentally new topological magnetization configurations, the process-es of skyrmion nucleation, manipulation, annihilation and detection with a view to their application as parts of memory devices, and their potential integration in broad-band spin dynamic and logic devices.

Published
2020

128. Disordered skyrmion phase stabilized by magnetic frustration in a chiral magnet

Author

Karube, Kosuke, primary, White, Jonathan S., additional, Morikawa, Daisuke, additional, Dewhurst, Charles D., additional, Cubitt, Robert, additional, Kikkawa, Akiko, additional, Yu, Xiuzhen, additional, Tokunaga, Yusuke, additional, Arima, Taka-hisa, additional, Rønnow, Henrik M., additional, Tokura, Yoshinori, additional, and Taguchi, Yasujiro, additional

Published
2018
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129. Singlet state formation and its impact on the magnetic structure in the tetramer system SeCuO3

Author

Cvitanić, Tonči, primary, Šurija, Vinko, additional, Prša, Krunoslav, additional, Zaharko, Oksana, additional, Kupčić, Ivan, additional, Babkevich, Peter, additional, Frontzek, Matthias, additional, Požek, Miroslav, additional, Berger, Helmuth, additional, Magrez, Arnaud, additional, Rønnow, Henrik M., additional, Grbić, Mihael S., additional, and Živković, Ivica, additional

Published
2018
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132. Chemical tunnel-splitting-engineering in a dysprosium-based molecular nanomagnet

Author

Sørensen, Mikkel A., primary, Hansen, Ursula B., additional, Perfetti, Mauro, additional, Pedersen, Kasper S., additional, Bartolomé, Elena, additional, Simeoni, Giovanna G., additional, Mutka, Hannu, additional, Rols, Stéphane, additional, Jeong, Minki, additional, Zivkovic, Ivica, additional, Retuerto, Maria, additional, Arauzo, Ana, additional, Bartolomé, Juan, additional, Piligkos, Stergios, additional, Weihe, Høgni, additional, Doerrer, Linda H., additional, van Slageren, Joris, additional, Rønnow, Henrik M., additional, Lefmann, Kim, additional, and Bendix, Jesper, additional

Published
2018
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134. Prototype of the novel CAMEA concept—A backend for neutron spectrometers

Author

Markó, Márton, Groitl, Felix, Birk, Jonas Okkels, Freeman, Paul Gregory, Lefmann, Kim, Christensen, Niels Bech, Niedermayer, Christof, Jurányi, Fanni, Lass, Jakob, Hansen, Allan, Rønnow, Henrik M., Markó, Márton, Groitl, Felix, Birk, Jonas Okkels, Freeman, Paul Gregory, Lefmann, Kim, Christensen, Niels Bech, Niedermayer, Christof, Jurányi, Fanni, Lass, Jakob, Hansen, Allan, and Rønnow, Henrik M.

Abstract

The continuous angle multiple energy analysis concept is a backend for both time-of-flight and analyzer-based neutron spectrometers optimized for neutron spectroscopy with highly efficient mapping in the horizontal scattering plane. The design employs a series of several upward scattering analyzer arcs placed behind each other, which are set to different final energies allowing a wide angular coverage with multiple energies recorded simultaneously. For validation of the concept and the model calculations, a prototype was installed at the Swiss neutron source SINQ, Paul Scherrer Institut. The design of the prototype, alignment and calibration procedures, experimental results of background measurements, and proof-of-concept inelastic measurements on LiHoF4 and h-YMnO3 are presented here.

Published
2018

135. Dispersive magnetic and electronic excitations in iridate perovskites probed by oxygen K-edge resonant inelastic x-ray scattering

Author

Lu, Xingye, Olalde-Velasco, Paul, Huang, Yaobo, Bisogni, Valentina, Pelliciari, Jonathan, Fatale, Sara, Dantz, Marcus, Vale, James G, Hunter, E C, Chang, Johan, Strocov, Vladimir N, Perry, R S, Grioni, Marco, McMorrow, D F, Rønnow, Henrik M, Schmitt, Thorsten, Lu, Xingye, Olalde-Velasco, Paul, Huang, Yaobo, Bisogni, Valentina, Pelliciari, Jonathan, Fatale, Sara, Dantz, Marcus, Vale, James G, Hunter, E C, Chang, Johan, Strocov, Vladimir N, Perry, R S, Grioni, Marco, McMorrow, D F, Rønnow, Henrik M, and Schmitt, Thorsten

Abstract

Resonant inelastic x-ray scattering (RIXS) experiments performed at the oxygen K edge on the iridate perovskites Sr2IrO4 and Sr3Ir2O7 reveal a sequence of well-defined dispersive modes over the energy range up to ∼0.8eV. The momentum dependence of these modes and their variation with the experimental geometry allows us to assign each of them to specific collective magnetic and/or electronic excitation processes, including single and bimagnons, and spin-orbit and electron-hole excitons. We thus demonstrate that dispersive magnetic and electronic excitations are observable at the O K edge in the presence of the strong spin-orbit coupling in the 5d shell of iridium and strong hybridization between Ir 5d and O 2p orbitals, which confirm and expand theoretical expectations. More generally, our results establish the utility of O K-edge RIXS for studying the collective excitations in a range of 5d materials that are attracting increasing attention due to their novel magnetic and electronic properties. Especially, the strong RIXS response at O K edge opens up the opportunity for investigating collective excitations in thin films and heterostructures fabricated from these materials.

Published
2018

136. Chemical tunnel-splitting-engineering in a dysprosium-based molecular nanomagnet

Author

Danish Council for Independent Research, Agencia Estatal de Investigación (España), European Commission, Oticon Foundation, University of Stuttgart, German Research Foundation, Danish Research Council, Swiss National Science Foundation, Ministerio de Ciencia, Innovación y Universidades (España), Ministerio de Economía y Competitividad (España), Augustinus Foundation, Sørensen, Mikkel A., Hansen, Ursula B., Perfetti, Mauro, Pedersen, Kasper S., Bartolomé, Elena, Simeoni, Giovanna G., Mutka, Hannu, Rols, Stéphane, Jeong, Minki, Zivkovic, Ivika, Retuerto, María, Arauzo, Ana B., Bartolomé, Juan, Piligkos, Stergios, Weihe, Høgni, Doerrer, Linda H., Slageren, Joris van, Rønnow, Henrik M., Lefmann, Kim, Bendix, Jesper, Danish Council for Independent Research, Agencia Estatal de Investigación (España), European Commission, Oticon Foundation, University of Stuttgart, German Research Foundation, Danish Research Council, Swiss National Science Foundation, Ministerio de Ciencia, Innovación y Universidades (España), Ministerio de Economía y Competitividad (España), Augustinus Foundation, Sørensen, Mikkel A., Hansen, Ursula B., Perfetti, Mauro, Pedersen, Kasper S., Bartolomé, Elena, Simeoni, Giovanna G., Mutka, Hannu, Rols, Stéphane, Jeong, Minki, Zivkovic, Ivika, Retuerto, María, Arauzo, Ana B., Bartolomé, Juan, Piligkos, Stergios, Weihe, Høgni, Doerrer, Linda H., Slageren, Joris van, Rønnow, Henrik M., Lefmann, Kim, and Bendix, Jesper

Abstract

Total control over the electronic spin relaxation in molecular nanomagnets is the ultimate goal in the design of new molecules with evermore realizable applications in spin-based devices. For single-ion lanthanide systems, with strong spin-orbit coupling, the potential applications are linked to the energetic structure of the crystal field levels and quantum tunneling within the ground state. Structural engineering of the timescale of these tunneling events via appropriate design of crystal fields represents a fundamental challenge for the synthetic chemist, since tunnel splittings are expected to be suppressed by crystal field environments with sufficiently high-order symmetry. Here, we report the long missing study of the effect of a non-linear (C4) to pseudo-linear (D4d) change in crystal field symmetry in an otherwise chemically unaltered dysprosium complex. From a purely experimental study of crystal field levels and electronic spin dynamics at milliKelvin temperatures, we demonstrate the ensuing threefold reduction of the tunnel splitting.

Published
2018

137. Spin excitations and quantum criticality in the quasi-one-dimensional Ising-like ferromagnet CoCl2·2D2O in a transverse field

Author

Rønnow, Henrik M., Larsen, J., Schäffer, T. K., Hansen, U. B., Holm, S. L., Ahl, S. R., Toft-Petersen, R., Taylor, J., Ehlers, G., Jensen, J., Lefmann, K., and Christensen, N. B.

Abstract

We present experimental evidence for a quantum phase transition in the easy-axis S = 3/2 anisotropic quasione-dimensional ferromagnet CoCl2 · 2D2O in a transverse field. Elastic neutron scattering shows that the magnetic order parameter vanishes at a transverse critical field μ0Hc = 16.05(4) T, while inelastic neutron scattering shows that the gap in the magnetic excitation spectrum vanishes at the same field value, and reopens for H>Hc. The field dependence of the order parameter and the gap are well described by critical exponents β = 0.45 ± 0.09 and zν close to 1/2, implying that the quantum phase transition in CoCl2 · 2D2O differs significantly from the textbook version of a S = 1/2 Ising chain in a transverse field. We attribute the difference to weak but finite three-dimensionality of the magnetic interactions.

Published
2017
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138. Dispersive magnetic and electronic excitations in iridate perovskites probed by oxygen K -edge resonant inelastic x-ray scattering

Author

Lu, Xingye, primary, Olalde-Velasco, Paul, additional, Huang, Yaobo, additional, Bisogni, Valentina, additional, Pelliciari, Jonathan, additional, Fatale, Sara, additional, Dantz, Marcus, additional, Vale, James G., additional, Hunter, E. C., additional, Chang, Johan, additional, Strocov, Vladimir N., additional, Perry, R. S., additional, Grioni, Marco, additional, McMorrow, D. F., additional, Rønnow, Henrik M., additional, and Schmitt, Thorsten, additional

Published
2018
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139. Prototype of the novel CAMEA concept—A backend for neutron spectrometers

Author

Markó, Márton, primary, Groitl, Felix, additional, Birk, Jonas Okkels, additional, Freeman, Paul Gregory, additional, Lefmann, Kim, additional, Christensen, Niels Bech, additional, Niedermayer, Christof, additional, Jurányi, Fanni, additional, Lass, Jakob, additional, Hansen, Allan, additional, and Rønnow, Henrik M., additional

Published
2018
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140. Phase diagram of diluted Ising ferromagnet LiHoxY1 xF4

Author

Babkevich, P., Nikseresht, N., Kovacevic, I., Piatek, J. O., Dalla Piazza, B., Kraemer, C., Kramer, K. W., Prokes, K., Mat'As, S., Jensen, J., and Rønnow, Henrik M.

Subjects
Ising, ferromagnet, LiHoxY1 xF4
Abstract

We present a systematic study of the phase diagram of LiHoxY1-xF4 (0.25

Published
2016

142. Correction to Superparamagnetic Nanoparticles as High Efficiency Magnetic Resonance Imaging T2 Contrast Agent

Author

Sousa, Fernanda, primary, Sanavio, Barbara, additional, Saccani, Alessandra, additional, Tang, Yun, additional, Zucca, Ileana, additional, Carney, Tamara M., additional, Mastropietro, Alfonso, additional, Jacob Silva, Paulo H., additional, Carney, Randy P., additional, Schenk, Kurt, additional, Omrani, Arash O., additional, Huang, Ping, additional, Yang, Lin, additional, Rønnow, Henrik M., additional, Stellacci, Francesco, additional, and Krol, Silke, additional

Published
2017
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145. Superparamagnetic Nanoparticles as High Efficiency Magnetic Resonance Imaging T2 Contrast Agent

Author

Sousa, Fernanda, primary, Sanavio, Barbara, additional, Saccani, Alessandra, additional, Tang, Yun, additional, Zucca, Ileana, additional, Carney, Tamara M., additional, Mastropietro, Alfonso, additional, Jacob Silva, Paulo H., additional, Carney, Randy P., additional, Schenk, Kurt, additional, Omrani, Arash O., additional, Huang, Ping, additional, Yang, Lin, additional, Rønnow, Henrik M., additional, Stellacci, Francesco, additional, and Krol, Silke, additional

Published
2016
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147. Neutral Aminyl Radicals Derived from Azoimidazolium Dyes

Author

Eymann, Léonard Y. M., primary, Tskhovrebov, Alexander G., additional, Sienkiewicz, Andrzej, additional, Bila, José L., additional, Živković, Ivica, additional, Rønnow, Henrik M., additional, Wodrich, Matthew D., additional, Vannay, Laurent, additional, Corminboeuf, Clémence, additional, Pattison, Philip, additional, Solari, Euro, additional, Scopelliti, Rosario, additional, and Severin, Kay, additional

Published
2016
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