Topological Features in Magnetically-Ordered and Correlated Crystals

PhD Program

Speaker

Mikel García Díez

When

2025/06/27
11:30

Place

CFM Auditorium (Donostia / San Sebastían)

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PhD Thesis defense by Mikel García Díez

Supervisors: Maia García Vergniory  (DIPC Senior Researcher) & Juan Luis Mañes Palacios

Condensed Matter Physics: Topological materials

The analysis of topological phases in crystalline systems has experienced an intense development since the introduction of the topological quantum chemistry (TQC) framework, which has been extended to include magnetic materials thanks to the recent tabulation of the Shubnikov group representations. Nevertheless, many problems remain open, such as the study of correlated phases of matter. This work uses the new framework of magnetic TQC to analyze topological features in crystalline media and explores the application in systems with electronic correlations. With an enhanced version of the IrRep Python package for symmetry analysis of band structures, we begin studying the mirror-symmetry-protected nodal lines in Fe₃GeTe₂ and hcp-Co. In Fe₃GeTe₂, we also determine the origins of the strong anomalous Hall conductivity by understanding the interplay between spin-orbit coupling, ferromagnetism and symmetry. We also study the phase transitions in the FeSe superconductor via doping into FeTe0.55Se0.45 and a newly proposed method of uniaxial strain which allows us to select weak and strong topological insulating phases. Finally, we explore the application of TQC in the honeycomb Kitaev model to study flux-preserving excitations over the flux-less ground state, representing a way to analyze the topology of generalized excitations in a highly-correlated system.