Unexpected anisotropic compression-induced superconductivity in pristine 2H-MoTe2

Abstract

High-pressure application is crucial for shaping material properties and revealing novel phenomena. Materials undergo more unpredictable transitions in their crystal and electronic structures under nonhydrostatic/isotropic pressures than under hydrostatic conditions. However, limited knowledge regarding this behavior exists due to a scarcity of relevant studies. In this study, we systematically investigated the evolution of the structure and electronic states of pristine $2H\text{-MoT}{\mathrm{e}}_2$ in anisotropic pressure environments. Surprisingly, we observed anisotropic compression-induced superconductivity in this material, a phenomenon that is absent in quasihydrostatic environments. High-pressure x-ray diffraction and Raman spectroscopy measurements showed no structural phase transitions; however, an anomalous compressive behavior was observed along the $c$ axis. An anisotropic pressure model was proposed based on experimental conditions. First-principles calculations revealed that a strengthened anisotropic compression effect could enhance electron-phonon coupling by increasing the density of states on the Fermi level and softening the phonon modes, contributing to the emergence of superconductivity in $2H\text{-MoT}{\mathrm{e}}_2$. Our findings offer a route for inducing superconductivity, providing insights into the nature of superconductivity in transition metal dichalcogenides and other similar layered compounds under extreme conditions.