Evidence for weak electron confinement in spin valves having Co_(90)Fe_(10)/Cu/Co_(90)Fe_(10) trilayers

摘要

The temperature and spacer-layer thickness dependences of the free layer coupling field in spin valves having Co_(90)Fe_(10)/Cu/Co_(90)Fe_(10) pinned-/spacer-/free layer trilayer structures have been measured. Our data verify a previously made theoretical prediction that the coupling field depends on both the shape of the Fermi surface of the spacer layer and the degree of confinement of the magnetic carriers in the spacer quantum well. In weakly confining systems such as Co_(90)Fe_(10)/Cu/Co_(90)Fe_(10) the latter mechanism can be large in the temperature range of interest and can have a significant impact on the temperature and spacer-layer thickness dependence of interlayer coupling fields. Including both mechanisms we are able to quantify the contribution of both the oscillatory interlayer and the Neel coupling field as well as the temperature-dependent data for the phase of the oscillations.