Topic: Microscopic study of spin-orbit-induced Mott insulator in Ir oxides

Speaker: Prof. Dr. Seiji Yunoki

　　　   Computational Condensed Matter Physics Laboratory,
　　　　　   RIKEN Advanced Institute，RIKEN, Japan

Time: 14:30, (Thur.) Aug.18, 2011

Venue: Room 406, R&D Building, IMR CAS

Welcome to attend!

 

Microscopic study of spin-orbit-induced Mott insulator in Ir oxides

Motivated by recent experiments of a novel 5d Mott insulator in Sr₂IrO₄, we have studied the two dimensional three-orbital Hubbard model with a spin-orbit coupling. The variational Monte Carlo method is used to obtain the ground state phase diagram with varying an on-site Coulomb interaction U as well as the spin-orbit coupling. It is found that the transition from a paramagnetic metal to an antiferromagnetic (AF) insulator occurs at a finite U = U_MI, which is greatly reduced by a large spin-orbit coupling, characteristic of 5d electrons, and leads to the “spin-orbit-induced” Mott insulator. It is also found that the Hund’s coupling induces the anisotropic spin exchange and stabilizes the in-plane AF order. We have further studied the one-particle excitations using the variational cluster approximation, and revealed the internal electronic structure of this novel Mott insulator. These findings are in agreement with experimental observations on Sr₂IrO₄, and qualitatively different from those of extensively studied 3d Mott insulators. 

[1] H. Watanabe, T. Shirakawa, and S. Yunoki, Phys. Rev. Lett. 105, 216410 (2010). 

[2] T. Shirakawa, H. Watanabe, and S. Yunoki, arXiv:1106.0413 (2011). 

 

Bio: Dr. Seiji Yunoki received his M.S. degree (physics) from University of Tokyo and Ph.D. (applied physics) from Nagoya University. He was a postdoc fellow and a research scientist at National High Magnetic Field Laboratory, University of Gronning, SISSA, Oak Ridge National Laboratory, and University of Tennessee form 1996. He joined RIKEN Advanced Science Institute as an Associate Chief Scientist in 2008, and RIKEN Advanced Institute for Computational Science as a Team Leader in 2010. He has published more than 50 papers in Journals including Science and Physical Review Letters. These papers have been cited for more than 3,000 times, with 7 papers cited for over 100 times. His main research area is condensed matter physics and material physics. His present research interests focus on strongly correlated electrons, transition metal oxide heterostructure and spintronics.