Influence of misfit strain on the Goos-Hanchen shift upon reflection from a magnetic film on a nonmagnetic substrate

TL;DR

This theoretical study shows that misfit strain in a magnetic film on a nonmagnetic substrate can significantly alter the Goos-Hanchen shift of near-infrared light upon reflection, with effects depending on polarization and film thickness.

Contribution

It reveals the impact of mechanical misfit strain on the lateral shift of reflected light in a magnetic bilayer, highlighting effects near normal incidence and polarization dependence.

Findings

Strain can induce a significant lateral shift near normal incidence.

The lateral shift can be positive or negative depending on polarization and film thickness.

Magnetization effects are more prominent for TM polarization.

Abstract

The influence of the misfit strain on the lateral shift (Goos-Hanchen effect) experienced by a near-infrared electromagnetic wave upon reflection from the surface of a bilayer consisting of a magnetic, gyrotropic (i.e., whose permittivity tensor elements depend upon magnetization) yttrium-iron garnet film deposited on a nonmagnetic gadolinium-gallium garnet substrate is investigated theoretically. In the geometry of the transverse magneto-optical Kerr effect, it is shown that the mechanical strain near the geometrical film/substrate interface can induce a significant lateral shift of the beam for incidence angles close to normal incidence, where no shift appears in the absence of strain. Our calculations demonstrate positive as well as negative values of the lateral shift, depending on the incident light polarization and on the film thickness. In contrast to that of the misfit strain, the influence of the magnetization of the gyrotropic film on the lateral shift is more noticeable for a TM- than for a TE-polarized wave.