Lattice response and anomalous photoconductivity in Janus WSeTe under high pressure and shear stress

Janus material WSeTe exhibits unique electrical, optical, and structural properties arising from its asymmetric lattice structure, making it a promising candidate for applications in optoelectronics, spintronics, and energy catalysis. In this paper, we systematically investigate the Raman scattering and photoconductive behavior of WSeTe under high pressure/shear. The results demonstrate that WSeTe maintains excellent structural stability up to 30 GPa. Notably, we observe a negative photoconductivity emerging at the remarkably low pressure of 1.4 GPa—a highly innovative finding in Janus materials under high pressure, which is attributed to the pressure‑induced transformation of Se Te defects from shallow levels to deep‑level recombination centers. In addition, discontinuous resistance jumps are observed at 6.9, 15.0, and 19.1 GPa, respectively. Combined with Raman analysis, these jumps are interpreted as signatures of orbital-selective Mott transitions. During decompression, significant hysteresis is evident in both the photoconductive and resistive responses. This work provides critical experimental insights into the optoelectronic response mechanisms of Janus materials under extreme conditions and establishes a foundation for their potential applications in high-pressure environments.