Coexistence of topological semimetal states in holography
Haoqi Chu (Department of Applied Physics, College of Science, China Agricultural University, Qinghua East Road, Beijing, 100083, China, Department of Geographical Information Engineering, College of Land Science and Technology, China Agricultural University, Qinghua East Road, Beijing, 100083, China); Xuanting Ji (Department of Applied Physics, College of Science, China Agricultural University, Qinghua East Road, Beijing, 100083, China, School of Physical Sciences, and CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Zhongguancun East Road, Beijing, 100190, China); Ya-Wen Sun (Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, Zhongguancun East Road, Beijing, 100190, China, School of Physical Sciences, and CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Zhongguancun East Road, Beijing, 100190, China)
We introduce a holographic model that exhibits a coexistence state of the Weyl semimetal and the topological nodal line state, providing us with a valuable tool to investigate the system’s behavior in the strong coupling regime. Nine types of bulk solutions exhibiting different IR behaviors have been identified, corresponding to nine different types of boundary states. These nine states include four distinct phases, namely the Weyl-nodal phase, the gap-nodal phase, the Weyl gap phase and the gap-gap phase, four phase boundaries, which are the Weyl-Dirac phase, the gap-Dirac phase, the Dirac-gap phase and the Dirac-nodal phase, and finally a double critical point. A phase diagram is plotted that exhibits qualitative similarity to the one obtained in the weak coupling limit. The anomalous Hall conductivity, which serves as an order parameter, and the free energy are calculated, with the latter showing the continuity of the topological phase transitions within the system. Our study highlights the similarities and differences in such a topological system between the weak and strong coupling regimes, paving the way for further experimental observations.
