Pressure-driven phase transition induces simultaneous negative photoconductivity and superconductivity

Researchers discover simultaneous negative photoconductivity and superconductivity by pressure-driven phase transition
Phase diagrams and carrier concentration ne as a function of pressure during compression and decompression for superconducting and photoconducting PbSe0.5Te0.5. Credit: Wang Pei

A research team led by Prof. Wang Xianlong and Dr. Wang Pei from the Hefei Institutes of 麻豆淫院ical Science of the Chinese Academy of Sciences has discovered a concurrent negative photoconductivity (NPC) and superconductivity in PbSe0.5Te0.5 by pressure-induced structure transition. The study has been in Advanced Materials.

NPC is a unique phenomenon where the conductivity of a material decreases due to the trapping of charge carriers in localized states, leading to a reduction in the number of free carriers, which is contrary to the more common behavior of positive photoconductivity (PPC).

Though NPC holds great promise in next-generation semiconductor optoelectronics and its application potential has recently reached far beyond photodetection, the phenomenon has rarely been reported. In particular, concurrent NPC and are rarely observed at high-pressure due to the lack of in situ experimental measuring facilities.

In this study, the team systematically investigated the response of PbSe0.5Te0.5 to pressure modulation under visible-light and low-temperature stimuli using a self-developed facility. Through detailed experimental and theoretical approaches, the researchers examined how changes in the material's crystal and electronic structures influenced both its photoconductive and superconducting properties.

They found that the pressure-driven PPC鈥揘PC transition arises from a strong nonequilibrium distribution of excited carriers. This is due to an enhanced electron鈥損honon interaction resulting from the photothermal effect, which reduces carrier concentration and mobility.

Density functional theory (DFT) theory calculations proved that the dramatically enhanced p鈥損 and s鈥損 hybridizations lead to enhanced electron鈥損honon interplay at the Fermi level, facilitating the semiconductor-to-superconductor transition. Structure-dependent superconductivity and NPC are switchable by pressure-mediated electron鈥損honon interplay under illumination or cooling.

This study sheds light on the origin of superconductive and photoconductive transitions in versatile materials of lead chalcogenides.

More information: Dongxuan Han et al, Concurrent Pressure鈥怚nduced Superconductivity and Photoconductivity Transitions in PbSe0.5Te0.5, Advanced Materials (2024).

Journal information: Advanced Materials

Citation: Pressure-driven phase transition induces simultaneous negative photoconductivity and superconductivity (2025, February 17) retrieved 8 July 2025 from /news/2025-02-pressure-driven-phase-transition-simultaneous.html
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