Massive fermions with low mobility in antiferromagnet orthorhombic CuMnAs single crystals

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.

Spin-flop phase transition in the orthorhombic antiferromagnetic topological semimetal Cu0.95MnAs

“…We concluded that this magnetic structure breaks the S 2z symmetry, leading to the disappearance of Dirac fermions. This is consistent with a following study on CuMnAs single crystals based on the argument that the easy axis is in the ab plane [13]. Our first-principles calculations show that this magnetic order can support spin-polarized states, a much sought after property for spintronics.…”

Antiferromagnetic CuMnAs: Ab initio description of finite temperature magnetism and resistivity

“…[37]. We note, that weakly temperature-dependent behavior with negative slope above T N was observed for polycrystalline orthorhombic CuMnAs [28].…”

Mixed axial-gravitational anomaly from emergent curved spacetime in nonlinear charge transport

“…All momentum space integrals were carried out on a 350 × 350 × 350 grid in the first Brillouin zone, where convergence was verified when incremental increases in the grid size amounted to less than 5% difference in the integrated value. The anti-ferromagnetic spin configuration of the M n atoms was implemented in accordance with experimental findings on the commensurate AFM (c-AFM) structure in orthorhombic CuMnAs [60,61], with spins oriented along the b-axis. We recover the experimental result that the c-AFM order breaks the screw symmetry S 2z , while also breaking the R y nonsymmorphic reflection symmetry.…”

“…Therefore, PT materials are ideal candidates to investigate the AGA through their intrinsic nonlinear conductivity. On top of that, the only two remaining Hall contributions, σ dr and σ gr , behave differently under permutation of the spatial indices, so that the Drude contribution σ dr can be subtracted away, for example, by taking a combination σ We have calculated σ (2) and σ gr for the orthorohmbic phase of CuMnAs, which is antiferromagnetic and breaks P and T but preserves PT [60,61]. As shown in Fig.…”

“…The effective Hall angle is then γ = σ AHE σ ≈ 0.5%, where we used σ ≈ 10 4 S cm −1 according to Ref. [61].…”