Strain-enhanced superconductivity in topological Weyl semimetal MoTe₂

Recently, there have been reports of the existence of a superconducting edge state in T_d-MoTe₂, a topologically non-trivial type-II Weyl semimetal and intrinsic superconductor. Magnetic-field dependent oscillations in edge state critical current similar to the periodic oscillations observed in the Little-Parks experiment have been shown [1]. However, oscillatory features were only observed at ultralow temperature (20 mK) and in exfoliated flakes of 60-120 nm thickness, limiting the exploration of possible exotic topological properties of the superconducting edge states in more complex device configurations. Here, we show strain-induced T_c enhancement in MoTe₂ by depositing stressed thin films onto flakes (process-induced strain engineering), where T_c is increased from 100 mK to >1.8 K in 5-10 nm thick flakes of MoTe₂. We observe similar edge state oscillatory features, with an increase in the number of oscillatory modes and periods, all sustained to higher temperatures (>400 mK). These results lead us to suspect that strain may be used to tune edge state superconductivity alongside the expected enhancement of bulk T_c.

[1] W. Wang, et al. Science 368, 534 (2020)