Kramers doublet ground state in topological Kondo insulators

Abstract

We consider the simplest variant of a Kondo insulator where a doublet of localized f -electrons hybridizes with spin-degenerate conduction electrons. We analyse the symmetries of f -orbitals involved in the hybridization and point out that the effective four-band model of such systems provides further descriptions of clean Kondo insulators, namely the spin-texture of the surface states are described by a Z topological invariant. We discuss general conditions for the appearance of topological non-trivial states and implications for rare-earth based compounds. As an example, we derive the full phase diagram of tetragonal Kondo insulators. In particular, our findings describe the spin-textures in the physically interesting non-trivial topological phase, i.e. when the band-width of conduction electrons sets the largest energy scale, and a new weak topological phase appears as function of the normalized distance between bands' centers.

Fragility of the Kondo insulating gap against disorder: Relevance to recent puzzles in topological Kondo insulators

“…This includes a proper symmetric phase structure that leads to the topological characteristics of SmB 6 . In fact, the community has recently witnessed a renewed focus in the designing of model topological Hamiltonians for SmB 6 (and systems alike) [36][37][38][39][40][41]. Note, however, that this issue of global topology is a lower-energy physics emerging below the higher-energy local Kondo gap scale.…”

Hubbard model on the kagome lattice with time-reversal invariant flux and spin-orbit coupling

“…Therefore it is of hight interest to study the effect of the local Hubbard interaction on the topological properties of the system. In particular, the following aspects have been studied: the time reversal invariant Hofstadter-Hubbard model [35][36][37][38][39] , the Haldane-Hubbard model [40][41][42][43] , the Kane-Mele-Hubbard model [44][45][46][47] , the interacting Rice-Mele model 48 , the Bernevig-Hughes-Zhang Hubbard model 49,50 , Weyl-Hubbard model 51 , SU(3) systems with artificial gauge fields 52,53 , and the Kondo lattice model [54][55][56] .…”

Solvable Periodic Anderson Model with Infinite-Range Hatsugai-Kohmoto Interaction: Ground-states and beyond

“…25 E f is the energy level of felectron and the hybridization strength between c and felectron is V . (spin and site-dependent V is also permitted and it leads to non-trivial quantum topological phase such as topological Kondo insulator, [26][27][28][29][30] and Kondo liquid with hybridization node 31,32 ) Furthermore, chemical potential µ has been added to fix electron's density. N s is the number of sites.…”