On strong f-electron localization effect in topological kondo insulator

TL;DR

This paper investigates how strong f-electron localization influences the surface states of topological Kondo insulators, revealing that such localization is essential for surface metallicity and confirming the strong topological nature of these systems.

Contribution

It demonstrates, through mean-field calculations within the periodic Anderson model, that f-electron localization is crucial for surface metallicity and confirms the strong topological insulator character of generic TKIs.

Findings

Surface metallicity requires f-electron localization.

Surface states intersect the Fermi level within the spectral gap.

Odd number of surface state crossings indicates a strong topological insulator.

Abstract

We study strong f-electron localization effect on surface state of a generic topological Kondo insulator (TKI) system by performing a mean-field theoretic (MFT) calculation within the frame-work of periodic Anderson model (PAM) using slave-boson technique. The surface metallicity together with bulk insulation is found to require this type of localization. A key distinction between surface states in a conventional insulator and a topological insulator is that, along a course joining two time-reversal invariant momenta (TRIM) in the same BZ, there will be intersection of these surface states, even/odd number of times, with the Fermi energy inside the spectral gap. For even (odd) number of surface state crossings, the surface states are topologically trivial (non-trivial). The symmetry consideration and the pictorial representation of surface band structure obtained here show odd number of crossing leading to the conclusion that, at least within PAM framework, the generic system is a strong topological insulator.