Effect of Buffer and Cap Layer on Thermally Stable Perpendicular Magnetic Anisotropy in Buffer/CoFeB/MgO/Cap Structure

In this letter, we study the effect of buffer and cap layers on thermally stable perpendicular magnetic anisotropy (PMA) in a buffer/CoFeB/MgO/cap structure. Not only is the buffer layer crucial, but the type of cap layer also affects the thermal stability of PMA. Relative to the Ta samples, the W samples that adopt a W buffer or cap layer acquire a wider PMA thickness range for further increasing the PMA thermal stability in magnetic random-access memory applications. And similarly for the W buffer layer, the annealing temperature for the W cap layer also increases by 30 °C (from 270 °C to 300 °C). Via detailed anomalous Hall effect measurements, the thermal stability of PMA in buffer/CoFeB/MgO/cap was investigated. This work provides a promising way to obtain high thermal stability of PMA in CoFeB-MgO-based spintronic applications, and it is significant for designing next-generation information storage devices.