Irradiation-induced tailoring of the magnetism of CoFeB/MgO ultrathin films

We study perpendicularly magnetized Ta/CoFeB/MgO films and investigate whether their irradiation with light ions can improve their properties by inducing a different crystallization dynamics. We report the magnetization, anisotropy, g-factor, and damping dependence upon irradiation fluence and discuss their evolutions with collisional mixing simulations and its expected consequence on magnetic properties. We show that after a short irradiation at 100 °C, the anisotropy increases close to the value obtained by conventional high temperature annealing. Higher irradiation-induced increase of anisotropy can be obtained but with a detrimental effect on the damping that can be understood from spin-orbit contributions.

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