Anisotropic magnon damping by zero-temperature quantum fluctuations in ferromagnetic CrGeTe3

Lebing Chen, Chengjie Mao, Jae Ho Chung, Matthew B. Stone, Alexander I. Kolesnikov, Xiaoping Wang, Naoki Murai, Bin Gao, Olivier Delaire, Pengcheng Dai

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

Spin and lattice are two fundamental degrees of freedom in a solid, and their fluctuations about the equilibrium values in a magnetic ordered crystalline lattice form quasiparticles termed magnons (spin waves) and phonons (lattice waves), respectively. In most materials with strong spin-lattice coupling (SLC), the interaction of spin and lattice induces energy gaps in the spin wave dispersion at the nominal intersections of magnon and phonon modes. Here we use neutron scattering to show that in the two-dimensional (2D) van der Waals honeycomb lattice ferromagnetic CrGeTe3, spin waves propagating within the 2D plane exhibit an anomalous dispersion, damping, and breakdown of quasiparticle conservation, while magnons along the c axis behave as expected for a local moment ferromagnet. These results indicate the presence of dynamical SLC arising from the zero-temperature quantum fluctuations in CrGeTe3, suggesting that the observed in-plane spin waves are mixed spin and lattice quasiparticles fundamentally different from pure magnons and phonons.

Original languageEnglish
Article number4037
JournalNature Communications
Volume13
Issue number1
DOIs
StatePublished - Dec 2022

Funding

We thank Dr. Seiko Ohira-Kawamura for her help in experiments on AMATERAS and Prof. R. Q. Wu for discussions. The neutron scattering and sample growth work at Rice is supported by U.S. NSF-DMR-2100741 and by the Robert A. Welch Foundation under Grant No. C-1839, respectively (P.D.). The works of JHC was supported by the National Research Foundation (NRF) of Korea (Grant nos. 2020R1A5A1016518 and 2020K1A3A7A09077712). Work at Duke (first-principles modeling) was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, under Award No. DE-SC0019978. A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facilities operated by the Oak Ridge National Laboratory. The neutron experiment at the Materials and Life Science Experimental Facility of the J-PARC was performed under a user program proposal number 2020A0099.

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