Bi-quadratic interlayer exchange coupling in Co ₂MnSi/Ag/Co ₂MnSi pseudo spin-valve

Bi-quadratic interlayer exchange coupling is found below 100 K in a Co ₂MnSi/Ag/Co ₂MnSi current-perpendicular-to-plane pseudo spin valves. The bi-quadratic coupling constant J ₂ was estimated to be ∼-0.30 erg/cm ² at 5 K and the strong temperature dependence of the coupling strength points its likely origin to the loose spin model. Application of current of ∼2 × 10 ⁷ A/cm ² below 100 K leads to an increase in the magnetoresistance (MR), indicating current induced antiparallel alignment of the two magnetic layers. These results strongly suggest that the presence of the bi-quadratic interlayer exchange coupling causes the reduction of the magnetoresistance at low temperature and illustrates the importance of understanding the influence of interlayer exchange coupling on magnetization configuration in magnetic nanostructures.