Massive fermions with low mobility in antiferromagnet orthorhombic CuMnAs single crystals

We report the physical properties of orthorhombic $o\text{\ensuremath{-}}\mathrm{CuMnAs}$ single crystal, which is predicted to be a topological Dirac semimetal with magnetic ground state and inversion symmetry broken. $o\text{\ensuremath{-}}\mathrm{CuMnAs}$ exhibits an antiferromagnetic (AFM) transition with ${T}_N\ensuremath{\sim}312\phantom{\rule{0.28em}{0ex}}\mathrm{K}$. Further characterizations of magnetic properties suggest that the AFM order may be canted with the spin orientation in the $bc$ plane. Small isotropic magnetoresistance 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 $o\text{\ensuremath{-}}\mathrm{CuMnAs}$. 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 $o\text{\ensuremath{-}}\mathrm{CuMnAs}$ exhibit remarkably different features from those of Dirac fermions predicted in theory.