# Valence transition in topological Kondo insulator

## TL;DR

This paper explores valence and topological phase transitions in a topological Kondo insulator using slave-boson analysis, revealing complex first-order and continuous transitions influenced by Coulomb interactions and temperature.

## Contribution

It introduces a comprehensive phase diagram showing various valence, magnetic, and topological transitions driven by Coulomb correlation and temperature effects.

## Key findings

- First-order valence transition near topological transition
- Thermal valence transition from mixed valence to Kondo region
- Shift from continuous to first-order antiferromagnetic transition

## Abstract

We investigate the valence transition in three-dimensional topological Kondo insulator through slave-boson analysis of periodic Anderson model. By including the effect of intra-atomic Coulomb correlation $U_{fc}$ between conduction and local electrons, we find a first-order valence transition from Kondo region to mixed valence upon ascending of local level above a critical $U_{fc}$, and this valence transition usually occurs very close to or simultaneously with a topological transition. Near the parameter region of zero-temperature valence transition, rise of temperature can generate a thermal valence transition from mixed valence to Kondo region, accompanied by a first-order topological transition. Remarkably, above a critical $U_{fc}$ which is considerable smaller than that generating paramagnetic valence transition, the original continuous antiferromagnetic transition is shifted to first order one, at which a discontinuous valence shift takes place. Upon increased $U_{fc}$, the paramagnetic valence transition approaches then converges with the first-order antiferromagnetic transition, leaving an significant valence shift on the magnetic boundary. The continuous antiferromagnetic transition, first-order antiferromagnetic transition, paramagnetic valence transition and topological transitions are all summarized in a global phase diagram. Our proposed exotic transition processes can help to understand the thermal valence variation as well as the valence shift around the pressure-induced magnetic transition in topological Kondo insulator candidates and in other heavy-fermion systems.