Topological phase in a two-dimensional metallic heavy-fermion system

TL;DR

This paper reveals a hidden topological insulating state within a ferromagnetic metallic phase of a heavy-fermion system, characterized by a spin-selective gap and robust topological properties, analyzed through advanced theoretical methods.

Contribution

It uncovers a novel topological phase in a heavy-fermion system away from half-filling, combining RKKY, Kondo, and spin-orbit effects, with detailed theoretical analysis.

Findings

Presence of a topological insulating state within ferromagnetic metal

Robust topological properties over a wide chemical potential range

Detection of gapless chiral edge modes influenced by spin fluctuations

Abstract

We report on a topological insulating state in a heavy-fermion system away from half-filling, which is hidden within a ferromagnetic metallic phase. In this phase, the cooperation of the RKKY interaction and the Kondo effect, together with the spin-orbit coupling, induces a spin-selective gap, bringing about topologically non-trivial properties. This topological phase is robust against a change in the chemical potential in a much wider range than the gap size. We analyze these remarkable properties by using dynamical mean field theory and the numerical renormalization group. Its topological properties support a gapless chiral edge mode, which exhibits a non-Tomonaga-Luttinger liquid behavior due to the coupling with bulk ferromagnetic spin fluctuations. We also propose that the effects of the spin fluctuations on the edge mode can be detected via the NMR relaxation time measurement.