Magnetization-induced optical third-harmonic generation in Co and Fe nanostructures

Magnetization-induced optical third-harmonic generation (MTHG) is observed in magnetic nanostructures: Co and Fe nanolayers and granular films containing Co nanoparticles. Magnetization-induced variations of the MTHG characteristics in these nanostructures exceed the typical values of linear magneto-optical Kerr effect by at least an order of magnitude: the maximum of magnetic contrast in the MTHG intensity is up to 0.2, the angle of polarization rotation for MTHG is 10\ifmmode^\circ\else\textdegree\fi{}, and the relative phase shift is up to 100\ifmmode^\circ\else\textdegree\fi{}. Correlation between the concentration dependencies of magnetic contrast in MTHG intensity and coefficient of giant magnetoresistance is observed below the percolation threshold in ${\mathrm{Co}}_{x}{\mathrm{Ag}}_{1\ensuremath{-}x}$ films. This points out the probable relations between mechanisms of these transport and nonlinear magneto-optical phenomena.