Effect of VN buffer layer on the magnetic anisotropy of epitaxial Ni₈₀Fe₂₀thin films deposited on MgO (001) substrates

Abstract

This study incorporates the structural and magnetic characterization of epitaxial Ni80Fe20 films grown by direct current magnetron sputtering on MgO(001) and MgO(001)||VN(001) substrates. A series of samples grown with different N2 flow settings for the deposition of VN and similar permalloy deposition parameters was utilized to investigate the effect of morphological evolution and buffer layer induced strain on the magnetic properties of Ni80Fe20. X-ray diffraction analysis reveals an epitaxial nature of the VN(001) and Py(001) films grown on MgO substrates. Angular dependent magneto-optical Kerr effect characterization reveals a cubic anisotropy for Ni80Fe20 on MgO with a coercivity of ∼0.8 Gauss along the easy directions. Incorporating an epitaxial VN buffer, the structures showed a transition from a cubic to isotropic magneto-crystalline anisotropy with coercivity varying from 2.5 to 25 Gauss for Ni80Fe20 deposition on VN (with N2 varying from 5 to 12 sccm). The variation is attributed to the microstructural evolution of the Ni80Fe20 to 3D structures along with an induced structural strain.