发布日期:2018-01-08 作者:理学院


报告题目:Ground-state phase diagram of an anisotropic spin-1/2 model on the triangular lattice

报告人:王孝群教授,博导, 杰青


报告时间:201817日 下午 14:00-14:30


报告摘要:Motivated by a recent experiment on the rare-earth material YbMgGaO4 [Y. Li et al., Phys. Rev. Lett. 115, 167203 (2015)], which found that the ground state of YbMgGaO4 is a quantum spin liquid, we study the ground-state phase diagram of an anisotropic spin-1/2 model that was proposed to describe YbMgGaO4. Using the density matrix renormalization-group method in combination with the exact-diagonalization method, we calculate a variety of physical quantities, including the ground-state energy, the fidelity, the entanglement entropy and spin-spin correlation functions. Our studies show that in the quantum phase diagram, there is a 120 degrees. phase and two distinct stripe phases. The transitions from the two stripe phases to the 120 degrees. phase are of the first order. However, the transition between the two stripe phases is not of the first order, which is different from its classical counterpart. Additionally, we find no evidence for a quantum spin liquid in this model. Our results suggest that additional terms may also be important to model the material YbMgGaO4. These findings will stimulate further experimental and theoretical works in understanding the quantum spin-liquid ground state in YbMgGaO4.


王孝群,上海交通大学物理与天文系教授,博士生导师。2004年获得基金委杰出青年基金,2006年入选百千万人才工程,2007年获得科技部重大研究计划课题和教育部长江学者创新团队。20036月至201312月担任中国人民大学物理系系主任,201312月至20176月担任上海交通大学物理与天文学院院长。长期从事计算物理方法及其在凝聚态物理研究中的应用等领域的前沿研究,研究兴趣主要集中在低维强关联、介观系统性质的电子、磁性和输运特性以及量子信息等方面的理论研究,以及数值模拟方法的探讨、发展与应用等。研究成果发表在Physical Review Letters, Physical Review B等物理学主流TOP期刊,出版《密度矩阵重整化——物理学中的一种新数值方法》专著1部。