Spin wave study of magnetic perpendicular surface anisotropy in single crystalline MgO$\text{/}$Fe$\text{/}$MgO films

TL;DR

This study uses broadband ferromagnetic resonance to analyze perpendicular surface anisotropy in single crystalline Fe/MgO films, revealing interface-specific magnetic properties and contributions to overall anisotropy.

Contribution

It provides a detailed magnetic characterization of Fe/MgO films, distinguishing interface effects and their relation to oxidation states, advancing understanding of surface anisotropy in thin films.

Findings

Identification of exchange constant, cubic, uniaxial, and surface anisotropies.

Separation of interface contributions to surface anisotropy.

Evidence of different oxidation states affecting interface magnetic properties.

Abstract

Broadband ferromagnetic resonance is measured in single crystalline Fe films of varying thickness sandwiched between MgO layers. An exhaustive magnetic characterization of the films (exchange constant, cubic, uniaxial and surface anisotropies) is enabled by the study of the uniform and the first perpendicular standing spin wave modes as a function of applied magnetic field and film thickness. Additional measurements of non-reciprocal spin wave propagation allow us to separate each of the two interface contributions to the total surface anisotropy. The results are consistent with the model of a quasi-bulk film interior and two magnetically different top and bottom interfaces, a difference ascribed to different oxidation states.