Strain driven spin reorientation transition of ultra thin Co films

초록

When a magnetic layer is adjacent to a non-magnetic layer, the magnetic property of the magnetic film (and possibly that of the non-magnetic layer) may change due to a hybridization or dehybridization of the electronic band structure at or near the interface. Perturbations of the electronic band structure near an interface can be a result of a number of factors including a break in crystal symmetry, change of coordination number, or change in number density of atoms. Locally reduced atomic densities at interfaces compared to the bulk are predicted theoretically and observed experimentally. More recently, interfacial strain, via magnetostriction, has been found to be an important parameter in the control of magnetic properties of ultra-thin films. Specifically, interfacial strain between an ultra-thin magnetic film and a non-magnetic underlayer was observed to profoundly affect the magnetic anisotropy of the Co/Au/Cu(111) samples. In this talk, we will present our recent study of non-magnetic layer thickness dependence of Co magnetic anisotropy due to the interfacial strain. We observe that the moment of 8 ML Co is in-plane with 2 ML Au underlayer, however, we found the easy axis of magnetization of 8 ML Co to lie perpendicular to the plane when the Au underlayer is 5 ML in the Au/Co/Au/Cu(111) samples. For the Cu/Co/Au/Cu(111) samples, the magnetic moments transition (from in-plane to out-of-plane) occurred 5 ML Co thickness.