Large Anomalous Hall Effect in a Half-Heusler Antiferromagnet
T. Suzuki, Robin Michael Daub Chisnell, A. Devarakonda, Y.-T. Liu, W. Feng, D. Xiao, Jeffrey W. Lynn, J. G. Checkelsky
The quantum mechanical (Berry) phase of the electronic wavefunction has profound effects on spin-dependent behavior in solids [2,2]. In the context of electronic transport, the Berry phase plays a critical role as a fundamental origin of the anomalous [3,4] and spin Hall effects [5,6], including their quantized limits [7,9]. Theoretical and experimental studies have seen significant progress in understanding these effects in ferromagnetic systems, where the separation of Berry phase and extrinsic contributions has been established . Despite their apparent similarities, less is known about Berry phase effects in antiferromagnetic systems. Here we present a study of single crystals of face-centered-cubit (FCC) antiferromagnet GdPtBi that shows an anomalous Hall angle θAH>0.1 comparable to the largest anomalous Hall angles in bulk ferromagnets  and significantly larger than any previous report in antiferromagnetic systems . Comparing the field-dependent spin structure deduced from neutron scattering with the related cases of strongly frustrated pyrochlores [12,13] and non-centrosymmetric B20 systems with Skyrmionic textures [14,15] where spin-chirality effects are important, suggests that the mechanism in the present system belongs to a more general intrinsic class originating from the combination of spin-orbit coupling and magnetic texture in non-collinear antiferromagnetic systems . Furthermore, the half Heusler system to which GdPtBi belongs has been predicted to host topologically non-trivial states if distorted [17,18] or through realizing an emergent symmetry upon antiferromagnetic order ; the magnetic textures indicated by the measurements here imply pathways toward both of these new topological platforms.