Field-tuned quantum effects in a triangular-lattice Ising magnet

Yayuan Qin; Yao Shen; Changle Liu; Hongliang Wo; Yonghao Gao; Yu Feng; Xiaowen Zhang; Gaofeng Ding; Yiqing Gu; Qisi Wang; Shoudong Shen; Helen C Walker; Robert Bewley; Jianhui Xu; Martin Boehm; Paul Steffens; Seiko Ohira-Kawamura; Naoki Murai; Astrid Schneidewind; Xin Tong; Gang Chen; Jun Zhao

doi:10.1016/j.scib.2021.08.012

Field-tuned quantum effects in a triangular-lattice Ising magnet

Sci Bull (Beijing). 2022 Jan;67(1):38-44. doi: 10.1016/j.scib.2021.08.012. Epub 2021 Aug 25.

Authors

Yayuan Qin¹, Yao Shen², Changle Liu¹, Hongliang Wo³, Yonghao Gao¹, Yu Feng⁴, Xiaowen Zhang¹, Gaofeng Ding³, Yiqing Gu³, Qisi Wang⁵, Shoudong Shen¹, Helen C Walker⁶, Robert Bewley⁶, Jianhui Xu⁷, Martin Boehm⁸, Paul Steffens⁸, Seiko Ohira-Kawamura⁹, Naoki Murai⁹, Astrid Schneidewind¹⁰, Xin Tong¹¹, Gang Chen¹², Jun Zhao¹³

Affiliations

¹ State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China.
² State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China; Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
³ State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China; Shanghai Qizhi Institute, Shanghai 200232, China.
⁴ Institute of High Energy Physics, Chinese Academy of Sciences (CAS), Beijing 100049, China; Spallation Neutron Source Science Center, Dongguan 523803, China; Materials and Life Science Division, J-PARC Center, Tokai, Ibaraki 319-1195, Japan.
⁵ State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China; Physik-Institut, Universität Zürich, Zürich CH-8057, Switzerland.
⁶ ISIS Facility, Rutherford Appleton Laboratory, STFC, Chilton, Didcot, Oxon OX11 0QX, UK.
⁷ Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin D-14109, Germany.
⁸ Institut Laue-Langevin, Grenoble 9, Cedex 38042, France.
⁹ Materials and Life Science Division, J-PARC Center, Tokai, Ibaraki 319-1195, Japan.
¹⁰ Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Garching 85748, Germany.
¹¹ Institute of High Energy Physics, Chinese Academy of Sciences (CAS), Beijing 100049, China; Spallation Neutron Source Science Center, Dongguan 523803, China.
¹² State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China; Department of Physics and HKU-UCAS Joint Institute for Theoretical and Computational Physics at Hong Kong, The University of Hong Kong, Hong Kong, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China. Electronic address: gangchen.physics@gmail.com.
¹³ State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China; Shanghai Qizhi Institute, Shanghai 200232, China; Institute of Nanoelectronics and Quantum Computing, Fudan University, Shanghai 200433, China; Institute of Nanoelectronics and Quantum Computing, Fudan University, Shanghai 200433, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China. Electronic address: zhaoj@fudan.edu.cn.

PMID: 36545957
DOI: 10.1016/j.scib.2021.08.012

Abstract

We report thermodynamic and neutron scattering measurements of the triangular-lattice quantum Ising magnet TmMgGaO₄ in longitudinal magnetic fields. Our experiments reveal a quasi-plateau state induced by quantum fluctuations. This state exhibits an unconventional non-monotonic field and temperature dependence of the magnetic order and excitation gap. In the high field regime where the quantum fluctuations are largely suppressed, we observed a disordered state with coherent magnon-like excitations despite the suppression of the spin excitation intensity. Through detailed semi-classical calculations, we are able to understand these behaviors quantitatively from the subtle competition between quantum fluctuations and frustrated Ising interactions.

Keywords: Magnetic frustration; Neutron scattering; Quantum magnet; Transverse field Ising model.