报告时间：3月17日 中午12：15
报告地点：唐楼 B501
报告人：王达
报告题目: Anomalous phonon effect on electronic orders: a study of 2D Hubbard-Holstein model
摘要：Electron-phonon coupling plays an important role not only in conventional BCS superconductors, but also in high temperature superconductors in which electronic correlation is mostly studied. How electron-phonon coupling interacts with electronic correlation is a long-standing problem and needs careful study. We investigate their competition within functional renormalization group in a prototype Hubbard-Holstein model. At half-filling, we found spin-density-wave and charge-density-wave phases and the transition between them, while no superconducting phase arises. Upon finite doping, d-wave/s-wave superconductivity emerges in proximity to spin-density-wave/charge-density-wave phases. Counter-intuitively, we observe that lower-frequency Holstein-phonons are either less destructive, or even beneficial, to the various phases, resulting in a negative isotope effect.
