TY - JOUR
T1 - Pressure-Induced Superconductivity and Flattened Se6 Rings in the Wide Band Gap Semiconductor Cu2I2Se6
AU - Cai, Weizhao
AU - Lin, Wenwen
AU - Li, Long Hua
AU - Malliakas, Christos D.
AU - Zhang, Rong
AU - Groesbeck, Matthew
AU - Bao, Jin Ke
AU - Zhang, Dongzhou
AU - Sterer, Eran
AU - Kanatzidis, Mercouri G.
AU - Deemyad, Shanti
N1 - Funding Information:
The authors acknowledge Yansun Yao (University of Saskatchewan) for fruitful discussions on DFT calculations, Haozhe Liu (HPSTAR) for allowing us to use the plate DAC gearbox for helium loading, and Przemysław Dera (University of Hawaii at Manoa) for his kind demonstration of the ATREX software. We also acknowledge Z. Valy Vardeny for allowing us to use the superconducting magnet cryostat in his lab. We thank Sergy Tkachev for assistance with helium loading, Jesse Smith for tremendous experimental support, and Jared Coles and Jordan Lybarger for their help with high-pressure powder X-ray data collection. The high pressure single crystal X-ray diffraction data and powder X-ray diffraction data were collected at 13-BM-C of GeoSoilEnviroCARS (The University of Chicago, Sector 13) and at 16-ID-B of HPCAT (Sector 16), Advanced Photon Source (APS), Argonne National Laboratory, respectively. GeoSoilEnviroCARS is supported by the National Science Foundation-Earth Sciences (EAR-1634415) and Department of Energy-GeoSciences (DE-FG02-94ER14466). HPCAT operations are supported by DOE-NNSA’s Office of Experimental Sciences. Use of the COMPRES-GSECARS gas loading system and PX2 was supported by COMPRES under NSF Cooperative Agreement EAR-1661511 and by GSECARS through NSF Grant EAR-1634415 and DOE Grant DE-FG02-94ER14466. Work at Argonne (sample preparation, characterization, and crystal growth) is supported by the U.S. DOE, Office of Basic Energy Science, Materials Science and Engineering Division. Use of the Advanced Photon Source at Argonne National Laboratory was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Publisher Copyright:
© 2019 American Chemical Society.
PY - 2019/9/25
Y1 - 2019/9/25
N2 - 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: Se6 rings and Cu2I2 dimers, which are linked in a three-dimensional framework. Cu2I2Se6 exhibits a concurrent pressure-induced metallization and superconductivity at â¼21.0 GPa with critical temperature (Tc) of â¼2.8 K. The Tc monotonically increases within the range of our study reaching â¼9.0 K around 41.0 GPa. These observations coincide with unprecedented chair-to-planar conformational changes of Se6 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 Se6 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.
AB - 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: Se6 rings and Cu2I2 dimers, which are linked in a three-dimensional framework. Cu2I2Se6 exhibits a concurrent pressure-induced metallization and superconductivity at â¼21.0 GPa with critical temperature (Tc) of â¼2.8 K. The Tc monotonically increases within the range of our study reaching â¼9.0 K around 41.0 GPa. These observations coincide with unprecedented chair-to-planar conformational changes of Se6 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 Se6 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.
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U2 - 10.1021/jacs.9b06794
DO - 10.1021/jacs.9b06794
M3 - Article
C2 - 31480843
AN - SCOPUS:85072628274
VL - 141
SP - 15174
EP - 15182
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 38
ER -