The spin-orbit Mott insulator Sr3Ir2O7 provides a fascinating playground to explore insulator-metal transition driven by intertwined charge, spin, and lattice degrees of freedom. Here, we report high-pressure electric resistance and resonant inelastic x-ray scattering measurements on single-crystal Sr3Ir2O7 up to 63–65 GPa at 300 K. The material becomes a confined metal at 59.5 GPa, showing metallicity in the ab plane but an insulating behavior along the c axis. Such an unusual phenomenon resembles the strange metal phase in cuprate superconductors. Since there is no sign of the collapse of spin-orbit or Coulomb interactions in x-ray measurements, this novel insulator-metal transition is potentially driven by a first-order structural change at nearby pressures. Our discovery points to a new approach for synthesizing functional materials.
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The RIXS measurements are performed at sectors 30 ID-B and 27 ID-B of Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science user facility operated by Argonne National Laboratory (ANL) supported by the U.S. DOE Award No. DE-AC02-06CH11357. C. C. C. is supported by the Aneesur Rahman Postdoctoral Fellowship at ANL. H.-S. K. and M. J. H. were supported by the Basic Science Research Program through NRF (Grant No. 2014R1A1A2057202) and by Samsung Advanced Institute of Technology (SAIT). G. C. acknowledges NSF support via Grant No. DMR1265162. H.-k. M. acknowledges the support of DOE-BES under Award No. DE-FG02-99ER45775 and NSFC Grant No. U1530402. M. v. V. is supported by the U.S. DOE under Award No. DE-FG02-03ER46097, and by the Institute for Nanoscience, Engineering, and Technology at Northern Illinois University.
See Supplemental Material at http://link.aps.org/ supplemental/10.1103/PhysRevLett.116.216402, which includes Refs. [31 – 34], for detailed information on experimental settings, methods, and partial data analysis.
Ding, Yang; Yang, Liuxiang; Chen, Cheng-Chien; Kim, Heung-Sik; Han, Myung Joon; Luo, Wei; Feng, Zhenxing; Upton, Mary; Casa, Diego; Kim, Jungho; Gog, Thomas; Zeng, Zhidan; Cao, Gang; Mao, Ho-kwang; and van Veenendaal, Michel, "Pressure-Induced Confined Metal from the Mott Insulator Sr3Ir2O7" (2016). Physics and Astronomy Faculty Publications. 429.