Collective magnetic Higgs excitation in a pyrochlore ruthenate

npj Quantum Materials

Article

Dongjoon Song¹  Changyoung Kim¹  Jae Hyuck Lee¹  Dongjin Oh¹  Dirk Wulferding¹  Mi Kyung Kim¹  Minji Noh²  Sungkyun Choi³  Hyunyong Choi⁴  Seung Ryong Park⁵  Junkyoung Kim⁵  Heung-Sik Kim⁶  Yong Baek Kim⁷  Li Ern Chern⁷  Natalia B. Perkins⁸  Yang Yang⁸ 

[1] Center for Correlated Electron Systems, Institute for Basic Science, Seoul, Korea;Department of Physics and Astronomy, Seoul National University, Seoul, Korea;Center for Correlated Electron Systems, Institute for Basic Science, Seoul, Korea;Department of Physics and Astronomy, Seoul National University, Seoul, Korea;Institute of Applied Physics, Seoul National University, Seoul, Korea;Center for Integrated Nanostructure Physics, Institute for Basic Science, Suwon, Korea;Sungkyunkwan University, Suwon, Korea;Department of Physics and Astronomy, Seoul National University, Seoul, Korea;Institute of Applied Physics, Seoul National University, Seoul, Korea;Department of Physics, Incheon National University, Incheon, Korea;Department of Physics, Kangwon National University, Chuncheon, Korea;Department of Physics, University of Toronto, Toronto, ON, Canada;School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, USA;

关键词: ;   

DOI  :  10.1038/s41535-023-00572-9

 received in 2023-02-08, accepted in 2023-07-24,  发布年份 2023

来源: Springer

【 摘 要 】

The emergence of scalar Higgs-type amplitude modes in systems where symmetry is spontaneously broken has been a highly successful, paradigmatic description of phase transitions, with implications ranging from high-energy particle physics to low-energy condensed matter systems. Here, we uncover two successive high temperature phase transitions in the pyrochlore magnet Nd2Ru2O7 at TN = 147 K and T* = 97 K, that lead to giant phonon instabilities and culminate in the emergence of a highly coherent excitation. This coherent excitation, distinct from other phonons and from conventional magnetic modes, stabilizes at a low energy of 3 meV. We assign it to a collective Higgs-type amplitude mode, that involves bond energy modulations of the Ru4 tetrahedra. Its striking two-fold symmetry, incompatible with the underlying crystal structure, highlights the possibility of multiple entangled broken symmetries.

【 授权许可】

CC BY   
© Springer Nature Limited 2023

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