Slater Insulator in Iridate Perovskites with Strong Spin-Orbit Coupling

Q. Cui, J.-G. Cheng, W. Fan, A. E. Taylor, S. Calder, M. A. McGuire, J.-Q. Yan, D. Meyers, X. Li, Y. Q. Cai, Y. Y. Jiao, Y. Choi, D. Haskel, H. Gotou, Y. Uwatoko, J. Chakhalian, A. D. Christianson, S. Yunoki, J. B. Goodenough, and J.-S. Zhou

Phys. Rev. Lett. 117, 176603 – Published 20 October 2016

Abstract

The perovskite ${SrIrO}_{3}$ is an exotic narrow-band metal owing to a confluence of the strengths of the spin-orbit coupling (SOC) and the electron-electron correlations. It has been proposed that topological and magnetic insulating phases can be achieved by tuning the SOC, Hubbard interactions, and/or lattice symmetry. Here, we report that the substitution of nonmagnetic, isovalent ${Sn}^{4 +}$ for ${Ir}^{4 +}$ in the ${SrIr}_{1 - x} {Sn}_{x} O_{3}$ perovskites synthesized under high pressure leads to a metal-insulator transition to an antiferromagnetic (AF) phase at $T_{N} \geq 225 K$ . The continuous change of the cell volume as detected by x-ray diffraction and the $λ$ -shape transition of the specific heat on cooling through $T_{N}$ demonstrate that the metal-insulator transition is of second order. Neutron powder diffraction results indicate that the Sn substitution enlarges an octahedral-site distortion that reduces the SOC relative to the spin-spin exchange interaction and results in the type- $G$ AF spin ordering below $T_{N}$ . Measurement of high-temperature magnetic susceptibility shows the evolution of magnetic coupling in the paramagnetic phase typical of weak itinerant-electron magnetism in the Sn-substituted samples. A reduced structural symmetry in the magnetically ordered phase leads to an electron gap opening at the Brillouin zone boundary below $T_{N}$ in the same way as proposed by Slater.

Received 18 May 2016

DOI:https://doi.org/10.1103/PhysRevLett.117.176603

Physics Subject Headings (PhySH)

Metal-insulator transition Spin-orbit coupling

Iridates Perovskites

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Q. Cui¹, J.-G. Cheng^1,2,*, W. Fan³, A. E. Taylor⁴, S. Calder⁴, M. A. McGuire⁵, J.-Q. Yan^5,6, D. Meyers⁷, X. Li², Y. Q. Cai², Y. Y. Jiao¹, Y. Choi⁸, D. Haskel⁸, H. Gotou⁹, Y. Uwatoko⁹, J. Chakhalian¹⁰, A. D. Christianson^4,11, S. Yunoki^3,12,13, J. B. Goodenough², and J.-S. Zhou^2,†

¹Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
²Materials Science and Engineering Program, University of Texas at Austin, Austin, Texas 78712, USA
³Computational Condensed Matter Physical Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
⁴Quantum Condensed Matter Division, Oak Ridge National Laboratory, Tennessee 37831, USA
⁵Materials Science and Technology Division, Oak Ridge National Laboratory, Tennessee 37831, USA
⁶Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
⁷Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA
⁸Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
⁹Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Chiba 277-8581, Japan
¹⁰Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA
¹¹Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37966, USA
¹²Computational Materials Science Research Team, RIKEN Advanced Institute for Computational Science (AICS), Kobe, Hyogo 650-0047, Japan
¹³Computational Quantum Matter Research Team, RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan