Temperature dependence of the spin Hall angle and switching current in the nc-W(O)/CoFeB/MgO system with perpendicular magnetic anisotropy

Neumann L, Meier D, Schmalhorst J-M, Rott K, Reiss G, Meinert M. Temperature dependence of the spin Hall angle and switching current in the nc-W(O)/CoFeB/MgO system with perpendicular magnetic anisotropy. APPLIED PHYSICS LETTERS. 2016;109(14): 142405.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 vertical bar Theta(eff)(SH)vertical bar approximate to 0.22 is independent of temperature, whereas the switching current increases strongly at low temperature. The increase 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 approximate to 0.23 mJ/m(2), 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. Published by AIP Publishing