Dresden 2017 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 34: Spin Dynamics and Transport: Magnonics

MA 34.12: Vortrag

Mittwoch, 22. März 2017, 12:30–12:45, HSZ 04

Electrically Driven Bose-Einstein Condensation of Magnons in Antiferromagnets — Eirik Fjaerbu, •Niklas Rohling, and Arne Brataas — Department of Physics, Norwegian University of Science and Technology, NO-7491, Trondheim, Norway

We explore routes to realize electrically driven Bose-Einstein condensation of magnons in insulating antiferromagnets. Even in insulating antiferromagnets, the localized spins can strongly couple to itinerant spins in adjacent metals via spin-transfer torque and spin pumping [1]. Our model describes a system where a spin accumulation in an adjacent normal metal is aligned with the staggered field of the antiferromagnet. This spin accumulation controls the formation of steady-state magnon condensates. Compared to the earlier proposed ferromagnetic case [2,3], there are two significant differences for antiferromagnets: Firstly, two types of magnons exist in antiferromagnets, which carry opposite magnetic moments. Consequently, Bose-Einstein condensation can occur for either sign of the spin accumulation. Secondly, in antiferromagnets, the operating frequencies of the condensate are orders of magnitude faster than in ferromagnets.

[1] R. Cheng, J. Xiao, Q. Niu, and A. Brataas, Phys. Rev. Lett. 113, 057601 (2014)

[2] S. A. Bender, R. A. Duine, and Ya. Tserkovnyak, Phys. Rev. Lett. 108, 246601 (2012)

[3] S. A. Bender, R. A. Duine, A. Brataas, and Ya. Tserkovnyak, Phys. Rev. B 90, 094409 (2014)