Nonlinear Magneto-Optics of freestanding Fe monolayers from first principles

TL;DR

This paper calculates the nonlinear magneto-optical Kerr effect in freestanding Fe monolayers from first principles, revealing how structural and magnetic variations influence the nonlinear optical response.

Contribution

It provides the first ab initio calculations of nonlinear susceptibilities and Kerr angles for Fe monolayers, including effects of structure and spin-orbit coupling.

Findings

Nonlinear susceptibilities are highly sensitive to structural changes.

Spin-orbit coupling significantly affects tensor elements.

Second harmonic generation varies with surface orientation and magnetization direction.

Abstract

The nonlinear magneto-optical Kerr-effect (NOLIMOKE) is determined for freestanding Fe monolayers with several in-plane structures from first principles. Based on the theory of nonlinear magneto-optics by H\"ubner and Bennemann [Phys. Rev. B, {\bf 40}, 5973 (1989)] we calculate the nonlinear susceptibilities of the monolayers using the ab initio FLAPW-method WIEN95 with the additional implementation of spin-orbit coupling and the calculation of the dipole transition matrix elements appropriate for freestanding monolayers. We present results for the spectral dependence of the nonlinear susceptibility tensor elements and the resulting intensities and Kerr angles. Special emphasize is put on the effects of structural changes such as the variation of the lattice constant and different surface orientations. The influence of spin-orbit coupling on the tensor elements for different magnetization directions is presented as well as the azimuthal dependence of the intensities generated by several low index surfaces, showing the pronounced sensitivity of second harmonic generation to lateral structural changes as well as magnetic properties even in the monolayer range.