Topological Phase Transition in MoTe2: A Review

Transition metal dichalcogenides (TMDs) are a branch of 2D materials which in addition to having an "easy-to-exfoliate" layered structure, also host semiconducting, metallic, superconducting, and topological properties in various polymorphs with potential applications. MoTe2 is an example of such a TMD, which shows semiconducting (in 2H phase), metallic (in 1T ' phase), topological Weyl semimetallic, and superconducting behavior (in T-d phase). Consequently, an extensive amount of research has been done on MoTe2, particularly on the topological phase transition between the metallic-type 1T ' phase and the topological T-d phase. This phase transition has been reviewed and its association with the crystal structure, charge transport, and electronic band structure is elaborately discussed. Also, the effect of various stimuli like reduced dimensionality, pressure, charge doping, and chemical substitution, which affect the structural transition as well as the superconducting transition temperatures, is reviewed; thereby, suggesting certain correlations between the apparently unrelated structural and superconducting phase transitions. The review also brings out some open questions which are likely to interest the community to address the physics associated with the phase transition and its potential applications.