Electric and Magnetic Properties of Tungsten Doping in VO2/Ni multilayers

The effect of W doping in VO₂ on the structural, electrical, and magnetic properties of VO₂/Ni heterostructures through the VO₂ phase transition was studied. It is well-known that VO₂ has a Structural Phase Transition (SPT) coincident with a metal-insulator transition (MIT) around 340 K, from a low temperature insulating monoclinic (M) to a high temperature metallic rutile (R) structure [1]. Doping VO₂ with W is known to lower the transition temperature proportional to the doping percentage [2]. The SPT of VO₂ induces an inverse magnetoelastic effect that strongly modifies the coercivity and magnetization of the Ni films [3]. Doped films were grown using two techniques; reactive magnetron co-sputtering of V and W in an O₂ environment, and spin coating using a sol-gel process. Doped films showed both a shift in temperature and suppression of the MIT proportional to doping percentage consistent with previous studies. A sharp decrease in the coercivity at the shifted SPT is observed for all samples grown using the sol-gel technique. Doped samples grown using magnetron sputtering have not shown any magnetoelastic effect. 1. N.F. Mott, Rev. Mod. Phys. 40, 677 (1968). 2. Shibuya K. et al, Appl. Phys. Lett. 96 (2010). 3. J. De La Venta et al, Appl. Phys. Lett. 104 (2014).