Atomically Resolved Acoustic Dynamics Coupled with Magnetic Order in a Van der Waals Antiferromagnet
Year: 2026
Type: article
Abstract: ABSTRACT Magnetoelastic coupling in van der Waals (vdW) magnetic materials enables a unique interplay between the spin and lattice degrees of freedom. Characterizing the elastic responses with atomic and femtosecond resolution across the magnetic transition is essential for guiding the design of magnetically tunable actuators and strain‐mediated spintronic devices. Here, ultrafast X‐ray diffraction employed at a free‐electron laser reveals that the atomic displacements, wave vectors, and dispersion relations of acoustic phonon modes in a vdW antiferromagnet FePS 3 are coupled with the magnetic order, by tracking both in‐plane and out‐of‐plane Bragg peaks upon optical excitation across the Néel temperature ( T N ). One transverse mode shows that a quasi‐out‐of‐plane atomic displacement undergoes a significant directional change across T N . Its quasi‐in‐plane wave vector is derived by comparing the measured sound velocity and the first‐principles calculations. The other transverse mode is an interlayer shear acoustic mode whose amplitude is strongly enhanced in the antiferromagnetic phase, exhibiting eight times stronger amplitude than the longitudinal acoustic mode below T N . The atomically resolved characterization of acoustic phonon dynamics that couple with magnetic ordering opens opportunities for harnessing unique magnetoelastic coupling in vdW magnets on ultrafast timescales.
Source: Advanced Materials
Authors: Faran Zhou, Kyle Hwangbo, Sung Soo Ha, Xiao‐Wei Zhang, Sae Hwan Chun, Jaeku Park, Intae Eom, Qianni Jiang, Zekai Yang, Marc Zajac, Sungwon Kim, Sungwook Choi, Zhaodong Chu, Kyoung Hun Oh, Yifan Su, Alfred Zong, Elton J. G. Santos, Ting Cao, Jiun‐Haw Chu, Stephan O. Hruszkewycz, Nuh Gedik, Di Xiao, Hyunjung Kim, Xiaodong Xu, Haidan Wen
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $6,070
Funders: Materials Sciences and Engineering Division, National Science Foundation, U.S. Department of Energy, University of Washington, National Research Foundation, Ministry of Science and ICT, South Korea, Office of Science, Engineering and Physical Sciences Research Council, Division of Materials Research, Basic Energy Sciences
Awards: G1301677854, G1739289980, G210363251, ULTRAFAST CONTROL OF EMERGING ELECTRONIC PHENOMENA IN 2D QUANTUM, EPCC Tier 2 HPC Service, G3507390398, The UK Car-Parrinello HEC Consortium, G3958281630, G4285111415, G4329987448, G4515799968, MRSEC: UW Molecular Engineering Materials Center, G5807428289, Two-Dimensional Magnetic Materials for the Next Generation of Functional Device Platforms (2DMagnete), G6139170584, G6179197607, G7624836136, MRSEC: UW Molecular Engineering Materials Center
OpenAlex ID: W7127046559