Using exchange bias to extend the temperature range of square loop behavior in [PtCo] multilayers with perpendicular anisotropy

The temperature dependence of the magnetic properties of [PtCo] multilayers (ML), exhibiting perpendicular anisotropy, with and without exchange biasing with an antiferromagnet (AFM) has been investigated. Upon heating, a loss of the out-of-plane anisotropy and, consequently, of the remanence to saturation ratio is observed in these systems. However, such effect occurs at higher temperatures in the [PtCo] ML exchange coupled to the AFM than for the unbiased ML. This is attributed to the additional anisotropy induced to the ML by the ferromagnetic-antiferromagnetic exchange coupling. © 2005 American Institute of Physics.