Pressure-Induced Superconductivity in the Wide-Band-Gap Semiconductor Cu<sub>2</sub>Br<sub>2</sub>Se<sub>6</sub> with a Robust Framework
Weizhao Cai, Wenwen Lin, Yan Yan, Katerina P. Hilleke, Jared Coles, Jin‐Ke Bao, Jingui Xu, Dongzhou Zhang, Duck Young Chung, Mercouri G. Kanatzidis, Eva Zurek, Shanti Deemyad
Abstract
We report pressure-induced superconductivity in a ternary and nonmagnetic Cu-containing semiconductor, Cu2Br2Se6, with a wide band gap of 1.89 eV, in which the Cu and Br atoms generate infinite 21 helical chains along the c-axis and are linked by the cyclohexane-like Se6 rings to form a three-dimensional framework. We find that this framework is remarkably robust under compression, and the ambient-pressure phase survives at least to our experimental limit of 32.1 GPa. Concurrent semiconductor-to-metal transition and superconductivity are observed above 21.0 GPa. The superconducting temperature monotonically increases from 4.0 to 6.7 K at 40.0 GPa. First-principles calculations show that the emergence of superconductivity is associated with the formation of weak multicentered bonds that involve the increase in coordination of the Cu atoms and a subset of the Se atoms. The observation of superconductivity in this type of nonmagnetic transition-metal-based material will inspire the exploration of related new superconductors under pressure.