Speaker
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Ali G. MOGHADDAM
Ali G. MOGHADDAM : Surface States in Magnetic Topological Insulators: Magnetic Ordering and Interaction effects
Ali G. MOGHADDAM, ITampere University, Finland & Institute for Advanced Studies in Basic Sciences, Zanjan, Iran
Le résumé :
Magnetic topological insulators (MTIs) have the unique property of their surface states being profoundly influenced by magnetic ordering and many-body interactions. Breaking time-reversal symmetry in these systems opens a gap in the surface states, but the exact underlying mechanisms remain debated.
I will discuss the interplay between surface-state dispersion, gap formation, and interaction effects in MTIs. I will first show how magnon-mediated electron-electron interactions, which exhibit long-range behavior, can play a dominant role in shaping surface state properties. On surfaces perpendicular to the magnetic ordering, these interactions enhance the band gap beyond the non-interacting limit, while on parallel surfaces, they induce features resembling a massless-like gap.
Next, I will discuss another aspect of the electronic structure of MTIs in the MnBi2nTe3n+1 family, where magnetic ordering triggers a transition from hexagonal to trigonal Dirac cone warping and introduces energy splittings between surface states of opposite momenta. These splittings provide an alternative sensitive probe of magnetic ordering and surface magnetization direction, complementing traditional gap-based detection methods.