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MA: Fachverband Magnetismus

MA 37: Focus Session: Insulator Spintronics

MA 37.7: Hauptvortrag

Mittwoch, 3. April 2019, 18:30–19:00, H38

Tunable long distance spin transport in antiferromagnetic insulators — •Mathias Kläui — Institute of Physics, Johannes Gutenberg-University Mainz

We probe spin transport in insulating antiferromagnets, such as NiO [1,2], CoO [3] and hematite [4]. Spin currents are generated by heating as resulting from the spin Seebeck effect and by spin pumping measurements and we find in vertical transport short (few nm) spin diffusion lengths [2,3].

For hematite, however, we find in a non-local geometry that spin transport of tens of micrometers is possible. We detect a first harmonic signal, related to the spin conductance, that exhibits a maximum at the spin-flop reorientation, while the second harmonic signal, related to the Spin Seebeck conductance, is linear in the amplitude of the applied magnetic field [4]. The first signal is dependent on the direction of the Neel vector of the antiferromagnet and the second one depends on the induced magnetic moment due to the field. From the power and distance dependence, we unambiguously distinguish long-distance transport based on diffusion [4] from predicted spin superfluidity that can potentially be used for logic [5].

References: [1] L. Baldrati et al., PRB 98, 024422 (2018) [2] L. Baldrati et al. PRB 98, 014409 (2018) [3] J. Cramer et al., Nature Comm. 9, 1089 (2018) [4] R. Lebrun et al., Nature 561, 222 (2018). [5] Y. Tserkovnyak et al., PRL 119, 187705 (2017).