Massive fermions with low mobility in antiferromagnet orthorhombic CuMnAs single crystals

TL;DR

This study investigates the physical and magnetic properties of orthorhombic CuMnAs single crystals, revealing low mobility hole carriers and contrasting features with theoretical Dirac fermions, despite predictions of topological semimetal behavior.

Contribution

It provides experimental insights into the magnetic and transport properties of o-CuMnAs, highlighting differences from theoretical Dirac fermion predictions in topological semimetals.

Findings

Antiferromagnetic transition at ~312 K.

High-density, low-mobility hole carriers dominate transport.

Carriers have a much larger effective mass than typical topological semimetals.

Abstract

We report the physical properties of orthorhombic o-CuMnAs single crystal, which is predicted to be a topological Dirac semimetal with magnetic ground state and inversion symmetry broken. o-CuMnAs exhibits an antiferromagnetic transition with TN ~ 312 K. Further characterizations of magnetic properties suggest that the AFM order may be canted with the spin orientation in the bc plane. Small isotropic MR and linearly field-dependent Hall resistivity with positive slope indicate that single hole-type carries with high density and low mobility dominate the transport properties of o-CuMnAs. Furthermore, the result of low-temperature heat capacity shows that the effective mass of carriers is much larger than those in typical topological semimetals. These results imply that the carriers in o-CuMnAs exhibit remarkably different features from those of Dirac fermions predicted in theory.