Thermal stability of perpendicular exchange bias in [Pd/Ferromagnet]N/FeMn films

The dependencies of the annealing temperature and the stack number N on perpendicular exchange-biasing(H
ex
) and coercivity(H
c
) in [Pd/Co]
N
and [Pd/Co (or CoFe)]
N
/FeMn multilayers were investigated. The surface anisotropy was varied as a function of N with constant bulk anisotropy. It was found that H
ex
does not depend on the surface anisotropy, while Hc shows a strong dependence. Therefore, it is possible to tailor wide ranges of the H
c
(300 ~ 600 Oe) without varying H
ex
(250 ~ 300 Oe) through the single control parameter stack number N. After annealing the H
c
shows peak value at 350 °C in [Pd/Co] multilayers without FeMn, but the peak temperature is down to 250 °C for the exchange biased [Pd/F]
N
/FeMn samples.