Spin Transport Across Interfaces With the Non-Collinear Antiferromagnet Mn3Sn.

Non-collinear antiferromagnets such as Mn 3 Sn are promising materials for ultrafast spintronic applications due to their peculiar electronic structure and efficient spin-dependent transport phenomena. Here, we investigate magnetic ordering and ultrafast spin transport in c-axis oriented Mn 3 Sn thin films and Mn 3 Sn -based heterostructures with Pt and Ni 80 Fe 20 . Temperature-dependent magneto-optical Kerr effect measurements confirm thermally activated switching of the Mn 3 Sn cluster octupole moment near the Néel temperature, while preserving predominantly in-plane magnetic order. In Mn 3 Sn | Pt heterostructures, however, pronounced room-temperature ferromagnetic signatures are observed, including enhanced Kerr rotation and out-of-plane magnetization. Systematic magnetometry studies reveal the formation of an intermixed Mn 2 PtSn interfacial phase upon annealing. Ultrafast transport measurements using a sample with optimized interfaces show that optical excitation of Mn 3 Sn generates predominantly anomalous Nernst currents, with no detectable evidence of efficient spin-current injection into Pt. In contrast, Mn 3 Sn exhibits a significant inverse spin Hall conversion when driven by spin currents injected from Ni 80 Fe 20 , reaching approximately 10 % of the efficiency of Pt-based reference structures. The conversion efficiency is found to be independent of the relative orientation between ferromagnetic magnetization and antiferromagnetic octupole moment. Our results emphasize the importance of interface engineering for spintronic devices.