Large perpendicular exchange bias and high blocking temperature in Al-doped Cr₂O₃/Co thin film systems

Abstract

We investigated the effect of Al doping on the perpendicular exchange bias in Cr2O3/Co thin film systems. By Al doping, a large unidirectional anisotropy energy (JK ∼ 0.74 erg/cm2) and a high blocking temperature (TB) were obtained simultaneously. The variations in JK and TB induced by Al doping were discussed on the basis of Mauri's model and explained from an increase in magnetic anisotropy and a decrease in the exchange stiffness constant of Cr2O3. Our first-principles calculations suggest a factor to improve the magnetic anisotropy of Cr2O3 markedly, which is different from the previously established lattice strain effect.