Pressure-induced Superconductivity and Flattened Se{sub 6} Rings in the Wide Bandgap Semiconductor Cu{sub 2}I{sub 2}Se{sub 6}.

Journal Article · Wed Sep 25 00:00:00 EDT 2019 · Journal of the American Chemical Society

DOI:https://doi.org/10.1021/jacs.9b06794· OSTI ID:1571913

Cai, Weizhao; Lin, Wenwen; Li, Long-Hua; Malliakas, Christos D.; Zhang, Rong; Groesbeck, Matthew; Bao, Jin-Ke; Zhang, Dongzhou; Sterer, Eran; Kanatzidis, Mercouri G.; Deemyad, Shanti

The two major classes of unconventional superconductors, cuprates and Fe-based superconductors, have magnetic parent compounds, are layered, and generally feature square-lattice symmetry. We report the discovery of pressure-induced superconductivity in a nonmagnetic and wide band gap 1.95 eV semiconductor, Cu2I2Se6, with a unique anisotropic structure composed of two types of distinct molecules: Se-6 rings and Cu2I2 dimers, which are linked in a three-dimensional framework. Cu2I2Se6 exhibits a concurrent pressure-induced metallization and superconductivity at similar to 21.0 GPa with critical temperature (T-c) of similar to 2.8 K. The T-c monotonically increases within the range of our study reaching similar to 9.0 K around 41.0 GPa. These observations coincide with unprecedented chair-to-planar conformational changes of Se-6 rings, an abrupt decrease along the c-axis, and negative compression within the ab plane during the phase transition. DFT calculations demonstrate that the flattened Se-6 rings within the CuSe layer create a high density of states at the Fermi level. The unique structural features of Cu2I2Se6 imply that superconductivity may emerge in anisotropic Cu-containing materials without square-lattice geometry and magnetic order in the parent compound.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States)
• Sponsoring Organization: National Science Foundation (NSF); USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science - Office of Basic Energy Sciences - Materials Sciences and Engineering Division
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1571913
• Journal Information: Journal of the American Chemical Society, Vol. 141, Issue 38
• Country of Publication: United States
• Language: English