Temperature dependence of the perpendicular magnetic anisotropy in Ta/Co2FeAl/MgO structures probed by Anomalous Hall Effect

•Perpendicular magnetic anisotropy (PMA) is achieved in ultrathin Co2FeAl thin films.•Surface magnetic anisotropy shows an important increase with decreasing temperature.•Bulk magnetic anisotropy becomes non-negligible at low temperatures.•Surface magnetic anisotropy is the sole responsible for PMA.

We report a detailed study of the temperature dependence of the magnetic anisotropy in Ta/Co2FeAl/MgO structures by means of Anomalous Hall Effect measurements. The volume magnetic anisotropy, although negligible at room temperature, shows a non-negligible value at low temperatures and favors an in-plane easy magnetization axis. The surface magnetic anisotropy, which promotes the perpendicular magnetic easy axis, shows an increase from 0.76±0.05erg/cm2 at 300 K, up to 1.08±0.04erg/cm2 at 5 K, attributed to the evolution of the Co2FeAl layer saturation magnetization with temperature.