Search

We construct a lattice model for a cubic Kondo insulator consisting of one spin-degenerate d and f orbital at each lattice site. The odd-parity hybridization between the two orbitals permits us to obtain various trivial and topological insulating phases, which we classify in the presence of cubic symmetry. In particular, depending on the choice of our model parameters, we find a strong topological insulator phase with a band inversion at the X point, modeling the situation potentially realized in SmB6, and a topological crystalline insulator phase with trivial ℤ2 indices but nonvanishing mirror Chern numbers. Using the Kotliar-Ruckenstein slave-boson scheme, we further demonstrate how increasing interactions among f electrons can lead to topological phase transitions. Remarkably, for fixed band parameters, the f-orbital occupation number at the topological transitions is essentially independent of the interaction strength, thus yielding a robust criterion to discriminate between different phases. [ABSTRACT FROM AUTHOR]

The article discusses a study on the effect of strong interactions in a quantum spin Hall insulator on the honeycomb lattice. Exotic phase for large spin-orbit coupling and intermediate Hubbard interaction is also identified. The important theme that interesting phases arise in the regime of strong spin-orbit coupling and interactions is also highlighted.

Abstract: In this paper we review some connections recently discovered between topological insulators and certain classes of quantum spin liquids, focusing on two and three spatial dimensions. In two dimensions we show the integer quantum Hall effect plays a key role in relating topological insulators and chiral spin liquids described by fermionic excitations, and we describe a procedure for “generating” a certain class of topological states. In three dimensions we discuss interesting relationships between certain quantum spin liquids and interacting “exotic” variants of topological insulators. We focus attention on better understanding interactions in topological insulators, and the phases nearby in parameter space that might result from moderate to strong interactions in the presence of strong spin–orbit coupling. We stress that oxides with heavy transition metal ions, which often host a competition between electron interactions and spin–orbit coupling, are an excellent place to search for unusual topological phenomena and other unconventional phases. [Copyright &y& Elsevier]