# Putative hybridization gap in CaMn$_{2}$Bi$_{2}$ under applied pressure

## TL;DR

This study investigates how pressure influences the electronic and magnetic properties of CaMn₂Bi₂, revealing a pressure-enhanced hybridization gap and magnetic order, suggesting its potential as a Mn-based hybridization-gap semiconductor.

## Contribution

It provides experimental evidence of pressure-induced gap enhancement and magnetic order changes in CaMn₂Bi₂, highlighting its potential as a hybridization-gap semiconductor.

## Key findings

- Pressure increases the activation gap by about 70% at 20 kbar.
- Antiferromagnetic order is strengthened under applied pressure.
- CaMn₂Bi₂ exhibits characteristics similar to correlated narrow-gap semiconductors.

## Abstract

We report electrical transport measurements on CaMn$_{2}$Bi$_{2}$ single crystals under applied pressure. At ambient pressure and high temperatures, CaMn$_{2}$Bi$_{2}$ behaves as a single-band semimetal hosting N\'{e}el order at $T_{N}=150$~K. At low temperatures, multi-band behavior emerges along with an activated behavior typical of degenerate semiconductors. The activation gap is estimated to be $\Delta \sim 20$~K. Applied pressure not only favors the antiferromagnetic order at a rate of 0.40(2)~K/kbar, but also enhances the activation gap at $20$~kbar by about $70$~\%. This gap enhancement is typical of correlated narrow-gap semiconductors such as FeSi and Ce$_{3}$Bi$_{4}$Pt$_{3}$, and places CaMn$_{2}$Bi$_{2}$ as a Mn-based hybridization-gap semiconductor candidate. \textit{Ab initio} calculations based on the density functional theory are shown to be insufficient to describe the ground state of CaMn$_{2}$Bi$_{2}$.