Quadratic-in-magnetization magneto-optical spectroscopy

Abstract

The magneto-optic is a very old branch of physics. However, the subject is still progressing, either by using magneto-optical effect in a novel ways and by developing of new materials and meta-materials. One of the key experimental technique in field of magneto-optics is a magneto-optical spectrometer, determining magneto-optical spectra. Within this work, we are building a new magneto-optical spectrometer based on photoelastic modulator and magneto-optical effect calibration by small rotation of the specific optical elements. The setup allows to measure spectra of both linear and quadratic magneto-optical effects, and their individual contributions. The spectroscopy was applied to Heusler compound Co$_2$MnSi. On this material, Kerr rotation and Kerr ellipticity spectra of linear ($B_{s/p}K$) and quadratic ($A_{s/p}G_{44}$, $A_{s/p}G_s$) contributions were determined in spectral range 1.6--4.8\,eV. In our knowledge, those are the first measured spectra of $G$-elements.