Dresden 2017 – scientific programme
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MA: Fachverband Magnetismus
MA 47: Spin Hall Effects and Skyrmions I
MA 47.9: Talk
Thursday, March 23, 2017, 11:45–12:00, HSZ 04
Temperature dependence of the spin Hall angle and switching current in the nc-W(O)/CoFeB/MgO system with perpendicular magnetic anisotropy — Lukas Neumann, Daniel Meier, Jan Schmalhorst, Karsten Rott, Günter Reiss, and •Markus Meinert — Center for Spinelectronic Materials and Devices, Bielefeld University, Bielefeld, Germany
We investigated the temperature dependence of the switching current for a perpendicularly magnetized CoFeB film deposited on a nanocrystalline tungsten film with large oxygen content: nc-W(O). The effective spin Hall angle |ΘSHeff| ≈ 0.22 is independent of temperature, whereas the switching current increases strongly at low temperature. The increase can not be explained by the increased coercive field, but rather indicates that the current induced switching itself is thermally activated, in agreement with a recent theoretical prediction. The dependence of the switching current on the in-plane assist field suggests the presence of an interfacial Dzyaloshinskii-Moriya interaction with D ≈ 0.23 mJ/m2, intermediate between the Pt / CoFe and Ta / CoFe systems. We show that the nc-W(O) is insensitive to annealing, which makes this system a good choice for the integration into magnetic memory or logic devices that require a high-temperature annealing process during fabrication.