Anisotropy dispersion in the exchange-biased pinned layer of a spin valve prepared by 550 eV hydrogen-ion irradiation

By investigating angular dependence of resistance and applying the Boltzmann distribution to the anisotropy dispersion of the magnetization in an exchange-biased pinned layer, we quantized the intrinsic anisotropy dispersion σγ of spin valves. The σγ was estimated to be 0.412° for the as-deposited spin valve and 0.183° for the ion-irradiated spin valve. This indicates that the dispersion indeed narrowed when the spin valve was field-annealed or irradiated by 550 eV hydrogen ions under a magnetic field, which is consistent with our previous attribution to the significant improvement in both exchange anisotropy and giant magnetoresistance of spin valves thus treated. Our methodology can be applied for other spin devices characterized by angular dependence of resistance to determine useful device properties such as the intrinsic anisotropy dispersion and the exchange bias of the exchange-biased reference layer.