Spin‐mixing conductances: The influence of disorder

Spin‐transfer torque exerted on a magnetic layer can be viewed as a linear response to the spin accumulation inside an adjacent non‐magnetic layer, information about their response coefficient is provided by the complex spin‐mixing conductance C mix . Substitutional disorder is known to affect the spin‐dependent charge conductances and often reduces strongly the magnetoresistance. Here we examine its impact on C mix of several selected realistic systems. Recently predicted oscillations of C mix as a function of ferromagnetic layer thickness in Ni based junctions might be suppressed by interface interdiffusion, but presented ab initio calculations disprove this possibility. Halfmetallic character of the Heusler compound Co 2 MnSi is destroyed by often encountered antisite disorder; however the impact of this disorder to the predicted C mix is rather weak. Diluted magnetic semiconductor (Ga,Mn)As is an intrinsically disordered system, the analysis of calculations shows that the variation of C mix with substitutional Mn content can be understood in terms of the associated change of the number of carriers, whereas the variation with lattice defects is more complex. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)