?Magnetic end-states in a strongly-interacting one-dimensional topological Kondo insulator

A. DOBRY; A. LOBOS; A. MEZIO; C. GAZZA

Natal

Workshop; Latin American Workshop in Condensed Matter: Low Dimensional Topological Quantum Matter; 2015

International Institute of Physics

The recent discovery of topological insulators and their symmetry-protected boundary modes with exotic quasiparticle properties, has captured the attention of the physicists worldwide. However, as fascinating as these states are, the existing topological insulating states represent non-interacting systems. Adding strong interactions to the theory leads to significant complications. Therefore, understanding such strongly interacting topological phases is a fundamental open question in condensed matter physics. In this talk I will present the results of our recent work on a strongly correlated Kondo-Heisenberg model in one dimension that realizes a topological Kondo insulator. Based on bosonization and Renormalization Group technics I will show how a Mott charge gap appear as a dynamical effect by solving the renormalization group equations at two-loop order in the Kondo parameter, even in the case of a non-interacting conduction band (Hubbard parameter U = 0). Furthermore, at low enough temperatures, I will show that the system maps onto a spin-1/2 ladder with local ferromagnetic interactions along the rungs, effectively locking the spin degrees of freedom into a spin-1 chain with frozen charge degrees of freedom. This structure behaves as a spin-1 Haldane chain, a prototypical interacting topological spin model, and features two magnetic spin-1/2 end states for chains with open boundary conditions. Our analysis allows deriving an insightful connection between topological Kondo insulators in one spatial dimension and the well-known physics of the Haldane chain, showing that the ground state of the former is qualitatively different from the predictions of the naïve mean-field theory.