Pressure-Induced Confined Metal from the Mott Insulator Sr3Ir2O7
  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. 
Yang Ding, Liuxiang Yang, Cheng-Chien Chen, Heung-Sik Kim, Myung Joon   Han, Wei Luo, Zhenxing Feng, Mary Upton, Diego Casa,...
cond-mat.str-el