Regensburg 2019 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 37: Focus Session: Insulator Spintronics

MA 37.4: Hauptvortrag

Mittwoch, 3. April 2019, 17:15–17:45, H38

Spintronics at interfaces of insulators and non-magnetic metals - magnon Bose-Einstein condensation and induced superconductivity — •Niklas Rohling, Eirik Løhaugen Fjaerbu, and Arne Brataas — Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, NO-7491, Trondheim, Norway

The coupling between a normal metal (NM) on one side and an antiferromagnetic (AFI) or ferromagnetic insulator (FI) on the other side allows for spin transport through the interface via spin pumping and spin transfer torque (STT). We describe this coupling by a Heisenberg exchange Hamiltonian and perfectly matching lattices. The coupling of the electronic and magnonic states then depends crucially on their amplitude at the interface. We discuss briefly the possibility of generating a magnon Bose-Einstein condensate via STT [1,2]. Then we focus on a model describing superconductivity induced by interfacial coupling to magnons in a FI-NM-FI trilayer [3]. The electron-magnon interaction at the interfaces induces electron-electron interactions, which in turn can result in p-wave superconductivity. We solve the gap equation numerically, estimate the interface coupling strength for yttrium iron garnet (YIG)-Au-YIG and EuO-Au-EuO trilayers, and find critical temperatures in an experimentally accessible range.

[1] Bender et al., Phys. Rev. Lett. 108, 246601 (2012); Phys. Rev. B 90, 094409 (2014).

[2] Fjærbu, Rohling, Brataas, Phys. Rev. B 95, 144408 (2017).

[3] Rohling, Fjærbu, Brataas, Phys. Rev. B 97, 115401 (2018).