Coercivity enhancement in VO2/Ni bilayers due to interfacial stress.

We studied the temperature dependence of the magnetic properties of VO2/Ni bilayers deposited on three different substrates. The temperature induced VO2 transformation from a monoclinic to a rutile structure induces strain in the Ni film. Due to an inverse magnetostrictive effect, the coercivity of the Ni films is strongly modified. The morphology of the films is influenced by the substrate choice and has a strong impact on the magnetic properties. Ni films grown on top of rutile VO2 show a reversible change in the coercivity and a strong enhancement of the coercivity near the transition temperature. The coercivity enhancement of Ni is associated with the phase coexistence observed in the VO2 first order phase transition. [ABSTRACT FROM AUTHOR]