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$_{ 2}$.
Categories: cond-mat.str-el