Title

Pressure-Densified New Rhombohedral Phase of Eusn2as2

Document Type

Article

Publication Date

12-7-2021

Publication Title

Physical Review B

Volume

104

Issue

22

Abstract

The magnetic topological insulator EuSn2As2 is known to crystallize in a Bi2Te3-type layered structure in rhombohedral symmetry at ambient conditions and undergo a structural phase transition toward a monoclinic β phase under increasing pressure. Here, we identify by ab initio calculations a new high-pressure rhombohedral structure (termed the γ phase) in R3¯m symmetry comprising Sn-As-As-Sn linear chains along the z 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 β phase above 11 GPa. Simulated x-ray diffraction patterns provide an excellent match to the previously unexplained distinct diffraction peak around 14.7∘ found in experiments for EuSn2As2 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.

Controlled Subject

Topological insulators

Disciplines

Health and Medical Physics | Medical Biophysics

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