FMR studies of magnetic properties of Co and Fe thin films on Al2O3 and MgO substrates

Abstract

The effect of substrates on the magnetic properties has been studied for Co and Fe films both on Al2O3 (112̄0) and MgO (001) substrates by using ferromagnetic resonance techniques. For Fe(001)/MgO(001) samples the thickness dependence of the magnetocrystalline constant and of the effective magnetization values have been determined from the in-plane angular variation of the resonance field H0. Different reasons for the thickness dependencies of these parameters are discussed. For Co(111)/Al2O3(112̄0) the angular variation of H0 exhibits an uniaxial anisotropy, for which several causes are discussed. For Co(112̄0)/MgO(100) a four-fold in-plane anisotropy was observed which is due to the twinned structure of these samples.

Interlayer magnetic coupling in Fe/MgO junctions characterized by vector magnetization measurements combined with polarized neutron reflectometry

“…The magnetic properties of Fe films deposited on MgO are known to be thickness dependent: a decrease in the crystalline anisotropy with decreasing thickness L has been indeed observed. [26][27][28][29] It has been attributed to a 1 / L contribution arising from surface anisotropy due to strains induced by the mismatch between film and substrate. 28,29 The recovering of the bulk properties for a 35-nm-thick film agrees with a previous study where the 1 / L term is found to be smaller for films prepared at 470 K than at room temperature.…”

“…[26][27][28][29] It has been attributed to a 1 / L contribution arising from surface anisotropy due to strains induced by the mismatch between film and substrate. 28,29 The recovering of the bulk properties for a 35-nm-thick film agrees with a previous study where the 1 / L term is found to be smaller for films prepared at 470 K than at room temperature. In the same manner, in our case, the annealing at 450°C can reduce the distance from the film surface where relaxation occurs.…”

Epitaxy, magnetic and tunnel properties of transition metal/MgO(001) heterostructures

“…Due to their epitaxial character, the expected in-plane cubic anisotropy has experimentally been found in the Fe/MgO(001) system, with an in-plane anisotropy and the easy axis along the 100 in plane directions. Early works of Goryunov et al [96,97] determined the magnetic anisotropy for Fe films of different thicknesses sputtered on MgO(001) substrates. Assuming the weak electronic interaction at the Fe-MgO interface, their goal was to explore the relevance of the mismatch induced strain on the magnetic anisotropy of the system.…”

Growth of Co ultrathin films on MgO(001)

“…MgO(0 0 1) is the substrate most frequently used due to its catalytic application and its stability at high temperature [6,7]; many works have been published on the growth of Co on MgO [1][2][3][8][9][10][11][12][13][14][15][16][17], with different experimental growth methods and many different analyzing techniques. Different studies demonstrate a 3D growth with fcc Co crystallographic structure at the early stage of growth [8,2].…”