Tuneable vertical hysteresis loop shift in Ni80Fe20/SrRuO3 heterostructures

A novel vertical hysteresis loop shift is observed for a bilayer thin film of Ni80Fe20/SrRuO3 (1:2 thickness ratio) on SrTiO3 substrate, after field cooled through the Curie temperature ~125 K of SrRuO3, whereas no shift is found for zero field cooled measurement. The vertical shift is noticed below ~125 K which increases with decreasing temperature and reaches a maximum of 33% at 2 K. The vertical shift is modelled closely using micromagnetic simulations. It is shown that the amount of vertical shift depends on the competition between the relative thicknesses and the anisotropies of the two films governed by Spring Thickness law and Imperial Law, respectively. We propose a generalized model of vertical shift which is applicable for other material systems, and hence could be informative for use of vertical shift in future spintronic devices.