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MA: Fachverband Magnetismus

MA 23: Functional Antiferromagnetism

MA 23.9: Vortrag

Dienstag, 17. März 2020, 11:45–12:00, HSZ 401

Anomalous and topological Hall effects in epitaxial thin films of the noncollinear antiferromagnet Mn₃Sn — •James M. Taylor¹, Anastasios Markou², Edouard Lesne¹, Pranava Keerthi Sivakumar¹, Peter Werner¹, Claudia Felser², and Stuart S. P. Parkin¹ — ¹Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle (Saale), Germany — ²Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany

Noncollinear antiferromagnets with a D0₁₉ hexagonal structure have garnered much attention for their potential applications in topological spintronics. Here, we report the deposition of continuous epitaxial thin films of such a material, Mn₃Sn, with both (0001) c-axis orientation and (4043) texture. In the latter case, the thin films exhibit a small uncompensated Mn moment in the basal plane, quantified via magnetometry. This cannot account for the large anomalous Hall effect simultaneously observed in these films, even at room temperature, with magnitude σ_xy (µ₀H = 0 T) = 21 Ω⁻¹cm⁻¹ and coercive field µ₀H_c = 1.3 T. We attribute the origin of this anomalous Hall effect to momentum-space Berry curvature arising from the symmetry-breaking inverse triangular spin structure of Mn₃Sn. Upon cooling through the transition to a glassy ferromagnetic state at around 50 K, a peak in the Hall resistivity close to the coercive field indicates the onset of a topological contribution to Hall effect. This is due to the emergence of a scalar spin chirality generating a real-space Berry phase, and is controllable using different field cooling conditions.