Experimental study of the x-ray linear dichroism of NiO films grown on Fe(001)

Abstract

X-ray linear dichroism (XLD) effects at the Ni ${L}_{2}$ edge of NiO films grown on Fe(001) were studied systematically as a function of NiO thickness (${d}_{\mathrm{NiO}}$), temperature, interfacial modulation, and Fe magnetization directions. We found that the Ni XLD signal exhibited an unusual dependence on ${d}_{\mathrm{NiO}}$. The XLD effect persists above the N\'eel temperature and exhibits a similar ${d}_{\mathrm{NiO}}$-dependence as the behavior at room temperature. On the other hand the Ni XLD signal reverses its sign as the Fe magnetization is switched by 90${}^{\ensuremath{\circ}}$. We propose a possible mechanism such that the Fe magnetostriction induces the NiO uniaxial crystal field to dominate the XLD magnitude in the NiO/Fe(001) system.