Simultaneous Development of Antiferromagnetism and Local Symmetry Breaking in a Kagome Magnet (Co0.45Fe0.55)Sn

Tsung Han Yang, Shang Gao, Yuanpeng Zhang, Daniel Olds, William R. Meier, Matthew B. Stone, Brian C. Sales, Andrew D. Christianson, Qiang Zhang

Research output: Contribution to journalArticlepeer-review

Abstract

CoSn and FeSn, two kagome-lattice metals, have recently attracted significant attention as hosts of electronic flat bands and emergent physical properties. However, current understandings of their physical properties are limited to knowledge of the average crystal structure. Here, we report the Fe-doping induced coemergence of the antiferromagentic (AFM) order and local symmetry breaking in (Co0.45Fe0.55)Sn. Rietveld analysis on the neutron and synchrotron X-ray diffraction data indicates A-type antiferromagnetic order with the moment pointing perpendicular to the kagome layers, associated with the anomaly in the MSn(1)2Sn(2)4 (M = Co/Fe) octahedral distortion and the lattice constant c. Reverse Monte Carlo (RMC) modeling of the synchrotron X-ray total scattering results captured the subtle local orthorhombic distortion involving off-axis displacements of Sn(2). Our results indicate that the stable hexagonal lattice above TN becomes unstable once the A-type AFM order is formed below TN. We argue that the local symmetry breaking has a magnetic origin, since the spatially varied M-Sn(2) bond lengths arise from out-of-plane magnetic exchange coupling Jc via the exchange pathway M-Sn(2)-M. Our study provides comprehensive information on the crystal structure in both long-range scale and local scale, unveiling unique coupling between AFM order, octahedral distortion, and hidden local symmetry breaking.

Original languageEnglish
Pages (from-to)34374-34382
Number of pages9
JournalJournal of the American Chemical Society
Volume146
Issue number50
DOIs
StatePublished - Dec 18 2024

Funding

This research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. The beam time was allocated to POWGEN on proposal number IPTS-26683.1. Neutron scattering data collection by A.D.C. and S.G. was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Science and Engineering Division. This research used resources at the 28-ID-1 (PDF) beamline of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract DE-SC0012704. Crystal growth and magnetometry measurements (BCS, WM) were supported by the Department of Energy, Office of Science, Basic Energy Sciences, Material Sciences and Engineering Division.

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