学术报告：Microscopic study of spin-orbit-induced Mott insulator in Ir oxides

标题：Microscopic study of spin-orbit-induced Mott insulator in Ir oxides
报告人： Prof. Seiji Yunoki  （柚木青司）
报告人单位：日本理化学研究所
时间：　９月３０日上午９点３０
地点：　田家炳楼南２０５会议室

摘要： 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).

报告人简介：

柚木青司博士在东京大学获得物理学硕士学位，在名古屋大学获得应用物理博士学位。从1996年至2008年，在美国国家强磁场实验室、荷兰Gronning大学，意大利SISSA，美国橡树岭国家实验室/田纳西大学从事研究（任博士后、研究助理教授）。柚木博士在2008年海归，任日本独立行政法人理化学研究所（和光本部）先进科学中心准主任研究员，独立领导计算凝聚态物理研究组。2010年在理化学研究所先进计算科学中心（筑波分部）任计算材料科学研究组组长。

柚木博士发表论文50余篇，其中包括1篇Science综述，14篇PRL。总引用3000余次，其中７篇论文引用超过100次。
1998年，柚木博士在国际上首次从理论上发现庞磁电阻锰氧化物中存在本征的电子相分离，对锰氧化物以及相关过渡金属氧化物的研究带来了深远的影响。
目前主要研究领域包括强关联电子、过渡金属氧化物异质结构、自旋电子学。

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.