主讲人：熊梓健（重庆大学）

题目：Dynamics in the planar pyrochlore lattice: bow-tie flat band and mixed‘t Hooft anomaly

时间：2021年12月20日（周一）下午15:00

地点：理工楼1226报告厅

联系人：赵继泽

报告摘要:

The quantum phase transition between Z 2 plaquette valence bound solid (PVBS) and superfluid (SF) phases on the planar pyrochlore lattice (square ice) is under debate, because the conventional deconfined theory does not support continuous one, but the numerical evidence is still not solid. Here, we propose the system can be effectively described by a 2+1 dimensional Abelian-Higgs model which may host the mixed‘t Hooft anomaly, so that the deconfinement can exist on the domain walls at the transition point. To verify it, we study the spin excitation spectra by combining stochastic analytic continuation and quantum Monte Carlo simulation. In both PVBS and SF phases, a flat band with bow-tie structure is observed and can be explained by group theoretic analysis. At the transition point, the spectra turn to be continuous and gapless, which indicates the topological excitations. From the snapshot of the spin configuration in real space, we found the existence of the domain wall in which the symmetries satisfy the anomaly. Meanwhile, a Luttinger liquid like continuum implies additional domain walls (point-defect) can emerge in the domain walls (line-defect) and take the role of deconfinement at transition point, as prediction of mixed‘t Hooft anomaly. Our work can build a new bridge between the topological gauge field theory and a strongly correlated system.

报告人简介：

熊梓健，重庆大学弘深青年教师。中山大学本科、直博，2020年获得理论物理专业博士学位。主要研究量子磁性、阻挫自旋系统和共振非弹性X光散射理论。