Abstract
The magnetic topological insulator is known to crystallize in a -type layered structure in rhombohedral symmetry at ambient conditions and undergo a structural phase transition toward a monoclinic phase under increasing pressure. Here, we identify by ab initio calculations a new high-pressure rhombohedral structure (termed the phase) in symmetry comprising Sn-As-As-Sn linear chains along the axis via the formation of As-As bonds in the AsSn/SnAs bilayers with strong anisotropic lattice distortion along the [001] orientation. This pressure-densified new rhombohedral phase has a metallic A-type antiferromagnetic ground state and is energetically more favorable than the original rhombohedral structure and the monoclinic phase above 11 GPa. Simulated x-ray diffraction patterns provide an excellent match to the previously unexplained distinct diffraction peak around found in experiments for above 13 GPa. These findings offer key insights into a new type of high-pressure phase of layered magnetic topological insulators, laying a foundation for further exploration of this intriguing class of materials.
- Received 22 July 2021
- Revised 6 October 2021
- Accepted 29 November 2021
DOI:https://doi.org/10.1103/PhysRevB.104.L220101
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