报告时间：2021年7月25日16:30-17:30
报告地点：阶三教室
讲座人：王义林
报告摘要：Many correlated metallic materials are described by Landau Fermi-liquid theory at low energies, but for Hund metals the Fermi-liquid coherence scale TFL is found to be surprisingly small. The simplest impurity model relevant for Hund metals is a three-channel spin-orbital Kondo model. In this lecture, I willshowhow to use the numerical renormalization group (NRG) method to compute its global phase diagram and use the conformal field theory (CFT) arguments to identify and understand the fixed points in the phase diagram. In this framework, TFL becomes arbitrarily small close to two new quantum critical points that we identify by tuning the spin or spin-orbital Kondo couplings into the ferromagnetic regimes. We find quantum phase transitions to a singular Fermi-liquid or a novel non-Fermi-liquid phase. The new non-Fermi-liquid phase shows frustrated behavior involving alternating overscreenings in spin and orbital sectors, with universal power laws in the spin (ω-1/5), orbital (ω+1/5) and spin-orbital (ω1) dynamical susceptibilities. These power laws, and the NRG eigenlevel spectra, can be fully understood using conformal field theory arguments, which also clarify the nature of the non-Fermi-liquid phase. Contents:
1. Introduction to Hund metal physics and the three-channel Hund-Kondo model
2. Introduction to NRG method and the non-abelian QSpace tensor library
3. Introduction to CFT arguments for identifying NRG fixed points
4. Compute the phase diagram of the three-channel Hund-Kondo model
5. Identify all the fixed points in the phase diagram
个人简介：
王义林，男，博士，华中科技大学材料科学与工程学院副教授、硕士生导师。
1991.9~ 1996.9华中理工大学 研究生(博士)毕业
1989.9~ 1992.9华中理工大学 研究生(硕士)毕业
1985.9 ~ 1989.9华中理工大学 本科(学士)
作为项目负责人，承担了国家自然科学基金项目两项，作为主要参与人，承担了国家自然基金重点项目、湖北省重大科技创新计划项目等项目，以及众多的企业课题，开发了汽车覆盖件模具CAD/CAM系统、精冲模CAD系统、热成形模具CAD系统，获得软件著作权4项。发表论文50多篇，主编著作2本。