Abstract
We use total scattering to study the reversible transition between the polar and nonpolar phases of layered taking place at 240 K. Whereas, macroscopically, the transition appears to be first order, locally, it is not. In particular, a great deal of the stacking sequence of Te-Mo-Te layers characteristic of the polar phase persists locally in the nonpolar phase, and vice versa, over a broad temperature range extending about 100 K both below and above the transition. The intermixing ratio for the two sequences evolves gradually across the transition temperature, consistent with a second-order transition behavior. The presence of coexisting local polar and nonpolar regions and the resulting variety of internal interfaces where the spatial inversion symmetry is broken may be behind some of the unusual electronic properties of , including its putative type-II Weyl semimetal state.
2 More- Received 7 January 2021
- Revised 12 February 2021
- Accepted 15 February 2021
DOI:https://doi.org/10.1103/PhysRevB.103.094101
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