Optical and magneto-optical properties of GdxFe(100-x) thin films close to the compensation point

Eva Jesenská,Jaroslav Hamrle,Roman Antoš,Takayuki Ishibashi,Lukáš Beran,Martin Pavelka,Jakub Zázvorka,Martin Veis

doi:10.1038/s41598-019-52252-z

Abstract

Unlike ferromagnetic materials, ferrimagnetic metals have recently received considerable attention due to their bulk perpendicular magnetic anisotropy, low net magnetization and tunable magnetic properties. This makes them perfect candidates for the research of recently discovered spin-torque related phenomena. Among other ferrimagnetic metals, GdFe has an advantage in relatively large magnetic moments in both sublattices and tunability of compensation point above the room temperature by small changes in its composition. We present a systematic study of optical and magneto-optical properties of amorphous GdxFe(100-x) thin films of various compositions (x = 18.3, 20.0, 24.7, 26.7) prepared by DC sputtering on thermally oxidized SiO2 substrates. A combination of spectroscopic ellipsometry and magneto-optical spectroscopy in the photon energy range from 1.5 to 5.5 eV with advanced theoretical models allowed us to deduce the spectral dependence of complete permittivity tensors across the compensation point. Such information is important for further optical detection of spin related phenomena driven by vicinity of compensation point in nanostructures containing GdFe.

Highlights

Unlike ferromagnetic materials, ferrimagnetic metals have recently received considerable attention due to their bulk perpendicular magnetic anisotropy, low net magnetization and tunable magnetic properties
The main purpose of our investigation was the determination of the complete permittivity tensors of GdxFe(100-x) thin films with various compositions (x = 18.3, 20.0, 24.7, 26.7) since their spectra provide a deeper look at optical and MO properties of this material
The spectral dependence of ε1r between 1.5 and 3 eV, where ε1r decreases its amplitude with increasing energy, differs from typical Drude-like behavior of metallic compounds, and is similar to the behavior of some transitions metals

Summary

Introduction

Ferrimagnetic metals have recently received considerable attention due to their bulk perpendicular magnetic anisotropy, low net magnetization and tunable magnetic properties. The main purpose of our investigation was the determination of the complete permittivity tensors of GdxFe(100-x) thin films with various compositions (x = 18.3, 20.0, 24.7, 26.7) since their spectra provide a deeper look at optical and MO properties of this material. From these results we determined the spectral dependence of the off-diagonal GdxFe(100-x) permittivity tensor elements ε2r and ε2i.

Results

Conclusion