Dresden 2014 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 85: Spincaloric Transport II (organized by MA)

TT 85.5: Talk

Thursday, April 3, 2014, 10:30–10:45, HSZ 04

Thermally driven domain wall motion — •Frank Schlickeiser, Ulrike Ritzmann, Denise Hinzke, and Ulrich Nowak — University Konstanz, 78457 Konstanz, Germany

The existence of thermally driven domain wall (DW) motion caused solely by magnonic spin currents was forecast on the basis of computer simulations [1]. Recently, this effect has been measured in a magnetic insulator [2]. A deeper understanding of this effect is of great interest, since it potentially opens the door for new ways to control and manipulate domain structures in spintronic devices.

We present an analytical calculation of the DW velocity as well as the Walker threshold within the framework of the Landau Lifshitz Bloch equation [3] describing the dynamics of the thermally averaged spin polarization on micromagnetic length scales. We demonstrate analytically that the temperature gradient leads effectively to a spin transfer torque where the domain wall is mainly driven by the temperature dependence of the exchange stiffness, or --- in a more general picture --- by the maximization of entropy. We find a linear dependence of the averaged DW velocity on the temperature gradient in agreement with the experiment [2]. The approximations in our analytical calculation are verified by numerical simulations.

We acknowledge financial support by the DFG through SFB 767.

References: [1] D. Hinzke and U. Nowak, Phys. Rev. Lett. 107, 027205 (2011), [2] W. Jiang et al., Phys. Rev. Lett. 110, 177202 (2013), [3] D. A. Garanin, Phys. Rev. B 55, 3050 (1997).