Regensburg 2019 – scientific programme
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MA: Fachverband Magnetismus
MA 46: Magnetic particles and clusters
MA 46.6: Talk
Thursday, April 4, 2019, 12:45–13:00, H52
Superparamagnetic limit of antiferromagnetic nanoparticles — Unai Atxitia1,2, Levente Rózsa3, Tobias Birk1, •Severin Selzer1, and Ulrich Nowak1 — 1Universität Konstanz, D-78457 Konstanz — 2Freie Universität Berlin, D-14195 Berlin — 3Universität Hamburg, D-20355 Hamburg
Antiferromagnetic materials are promising candidates for future spintronic devices. Compared to ferromagnets, they have no stray fields, a low susceptibility to external fields and faster spin dynamics. However, for many applications the size of the magnetic structures has to be scaled down to the nanometer regime. As for ferromagnets, the magnetic stability of antiferromagnetic nanoparticles will be limited by thermal excitations.
We investigate the superparamagnetic limit of antiferromagnetic nanoparticles theoretically, focusing on a comparison to the known properties of ferromagnetic particles. We find a drastically reduced thermal stability because of the exchange enhancement of the attempt frequencies and the effective damping during the antiferromagnetic switching process. We show that the order parameter in antiferromagnetic particles may strongly oscillate during the reversal at low damping values.