Change of Electronic Structure Induced by Magnetic Transitions in CeBi

TL;DR

This study investigates how magnetic transitions in CeBi influence its electronic structure, revealing temperature-dependent spectral changes linked to antiferromagnetic phase shifts and their impact on the Bi 6p and Ce 4f states.

Contribution

It provides a detailed analysis of the electronic structure changes in CeBi induced by magnetic phase transitions, combining optical conductivity measurements with band calculations.

Findings

Spectral peaks shift rapidly with temperature between 11 K and 25 K.

Second-order transition observed at 25 K from paramagnetic to single-layer antiferromagnetic phase.

First-order-like transition at 11 K from single-layer to double-layer antiferromagnetic phase.

Abstract

The temperature dependence of the electronic structure of CeBi arising from two types of antiferromagnetic transitions based on optical conductivity ($\sigma(\omega)$) was observed. The $\sigma(\omega)$ spectrum continuously and discontinuously changes at 25 and 11 K, respectively. Between these temperatures, two peaks in the spectrum rapidly shift to the opposite energy sides as the temperature changes. Through a comparison with the band calculation as well as with the theoretical $\sigma(\omega)$ spectrum, this peak shift was explained by the energy shift of the Bi $6p$ band due to the mixing effect between the Ce $4f \Gamma_8$ and Bi $6p$ states. The single-layer antiferromagnetic ($+-$) transition from the paramagnetic state was concluded to be of the second order. The marked changes in the $\sigma(\omega)$ spectrum at 11 K, however, indicated the change in the electronic structure was due to a first-order-like magnetic transition from a single-layer to a double-layer ($++--$) antiferromagnetic phase.