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MA: Fachverband Magnetismus
MA 9: Spin Excitations/Spin Torque
MA 9.5: Talk
Monday, March 16, 2015, 16:30–16:45, H 0112
Probing the linear relation of interfacial Dzyaloshinskii-Moriya interaction and Heisenberg exchange — Hans Nembach1, Justin Shaw1, •Mathias Weiler1,2, Emilie Jué1, and Thomas Silva1 — 1National Institute of Standards and Technology, Boulder, CO, USA — 2Walther-Meißner-Institut, Garching, Germany
The exchange interaction is the fundamental quantum-mechanical mechanism responsible for ferromagnetism. While the symmetric Heisenberg exchange favors the parallel alignment of spins, the anti-symmetric Dzyaloshinskii-Moriya interaction (DMI) is responsible for chiral magnetic ordering. Moriya calculated that the DMI and Heisenberg exchange interactions should be proportional to each other in the bulk solid, hematite. Up to now, this theoretically predicted proportionality was untested.
Here, we use optical spin-wave spectroscopy (Brillouin light scattering) to determine the DMI-induced asymmetric shift of the spin-wave dispersion for thermal Damon-Eshbach spin waves in a series of Ni80Fe20/Pt thin film bilayer samples [1]. This allows us to directly extract the magnitude and direction of the interfacial DMI. We compare the extracted DMI to the independently measured Heisenberg exchange integral. The Ni80Fe20-thickness-dependencies of both the microscopic symmetric- and antisymmetric-exchange are identical, as was originally proposed by Moriya for a bulk system. This allows to predict the influence of the DMI on spin-orbit torque applications.
Nembach et al. arXiv:1410.6243