Enabling magnetoelastic coupling in Ni/VO2 heterostructure by structural phase transition

Strain engineering is a popular approach for manipulating material properties through modifying crystal structures and/or electron-lattice interactions. In this work, we used a phase transition material, vanadium dioxide (VO2) as an active and reconfigurable substrate to generate a controllable strain. Amorphous ferromagnetic Ni thin films were deposited on the (010)-VO2/(0001)-Al2O3 substrates. It is observed that the magnetic moments of the Ni thin film were modulated by interfacing it with the VO2 thin film. We observed a hysteresis in the magnetic moment-temperature curves in the vicinity of the metal-insulator transition of the VO2 thin films at a low magnetic field bias (< 30 Oe). This result can be attributed to magnetoelastic coupling between the Ni and VO2 thin films through a reversible structural phase transition. As the bias field was increased, the hysteresis was suppressed and eventually disappeared. The competition between the magnetoelastic energy and external Zeeman energy can explain these behaviors. Our observations suggest a promising approach to dynamically controlling the properties of functional thin films by strain engineering.