Interplay of topology and correlation effects in electronic systems

• Main Authors: Chou, Po-Hao, 周柏豪
• Other Authors: Mou, Chung-Yu
• Format: Others
• Language: en_US
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/3qcxe3

博士 === 國立清華大學 === 物理學系 === 106 === In this thesis, we investigate the interplay of topological and correlation in electronic systems. Topological effects in three correlated electronic systems are examined: from Kondo-Dirac fermions in a topological Anderson lattice, inter-surface p-wave pairing in thin topological insulators, to strain induced superconducting pair density waves in graphene. It is shown that in a generalized Anderson lattice with spin-orbit type hy- bridization between conduction electrons and localized electrons, Dirac fermions emerge over large temperature and parameter regime between strong and weak topological in- sulating phases. The massless Dirac fermions form a critical point with nearby regime characterized by the Dirac liquids when Coulomb interaction for conduction electrons is in- cluded. In the system of topological insulators, we find that the interplay of geometry and superconducting instability leads to the possibility of forming topological superconductiv- ity due to inter-surface pairing by tuning the thickness of the thin topological insulators. Furthermore, it is shown that superconductivity on spherical surfaces can spontaneously generate vortices with a Majorana fermion at the center due to the curvature effect. Fi- nally, it is shown that ripples in graphene, if their amplitudes are large enough, generate topological flat bands. In the presence of strong Hubbard U interaction, we find that for a given wavelength of ripple, chiral d-wave superconductivity can be stablized even in slightly doped graphene. Most importantly, it is shown that superconducting pair density wave state emerges at a finite temperature regime with doubled wavelength.