Berlin 2015 – scientific programme

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MA: Fachverband Magnetismus

MA 9: Spin Excitations/Spin Torque

MA 9.4: Talk

Monday, March 16, 2015, 16:15–16:30, H 0112

Domain wall motion in temperature gradients caused by maximization of entropy — •Frank Schlickeiser, Ulrike Ritzmann, Unai Atxitia, Denise Hinzke, and Ulrich Nowak — University Konstanz, 78457 Konstanz, Germany

A theoretical understanding of thermally driven domain wall (DW) motion is of great interest, since it potentially opens the door for new ways to control and manipulate domain structures in spintronic devices. Based on the Landau Lifshitz Bloch equation [1], we present an analytical calculation of the DW velocity as well as the Walker threshold, where we find, that the domain wall is mainly driven by the temperature dependence of the exchange stiffness [2,3]. Additionally we show that the effect of the entropic torques should be larger than the angular momentum transfer from the magnon current [4,5]. Since our argument on thermodynamic principles, mainly the maximization of entropy, is rather general, it should not be restricted to transverse domain walls in ferromagnets only. Therefore, we will also discuss its applicability for different magnetic systems as antiferromagnets, where we expect the DW to move to hotter regions as well. We acknowledge financial support by the DFG through SFB 767. References: [1] D. A. Garanin, Phys. Rev. B 55, 3050 (1997), [2] D. Hinzke and U. Nowak, Phys. Rev. Lett. 107, 027205 (2011), [3] F. Schlickeiser, et al., Phys. Rev. Lett. 113, 097201 (2014), [4] W. Jiang et al., Phys. Rev. Lett. 110, 177202 (2013), [5] D. A. Kovalev et al., Europhys. Lett. 97, 67002 (2012).