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

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.

Boron-induced magneto-optical Kerr spectra and dielectric tensors in ferrimagnetic (Mn4N)B antiperovskite thin films

“…Here, the thicknesses of the (Mn 4 N)B and capping layers and the dielectric constants of (Mn 4 N)B (ε (Mn4N)B ) were the fitting parameters. Because the resistivity of (Mn 4 N)B films is conductive [37], ε (Mn4N)B is given by the Drude-Lorentz model [12,14,15,38],…”

“…Therefore, we analyzed samples with Al and Ta capping layers using the multi-sample analysis (MSA) mode to determine more accurate dielectric constants [41,42]. MSA allows us to fit ε (Mn4N)B by fixing the dielectric constant of the capping layer [14,43]. To verify the thicknesses of each layer obtained from SE, x-ray reflectivity (XRR) measurements were also performed at ambient temperature.…”

“…Magneto-optical (MO) spectroscopy has been extensively studied in many magnetic materials for the sensitive analysis of crystal structures and/or composition-dependent magnetic properties in alloys [1][2][3][4][5][6][7][8]. In addition to MO spectroscopy, spectroscopic ellipsometry (SE) has been employed to assess the optical and dielectric constants of magnetic films [9][10][11][12][13][14][15]. Jesenská et al discussed the inter-band transition of electrons with Fe 3d and Gd 5d states in GdFe films near the magnetic compensation point based on the full-dielectric tensors * Author to whom any correspondence should be addressed.…”

“…Jesenská et al discussed the inter-band transition of electrons with Fe 3d and Gd 5d states in GdFe films near the magnetic compensation point based on the full-dielectric tensors * Author to whom any correspondence should be addressed. [14]. Sharma et al studied the resistivity and electron scattering time from the Drude term of the dielectric function of CoFeB, which is related to the crystal structure of the film [15].…”

Enhancement of permittivity off-diagonal terms in rare earth transition metal / heavy metal hetero-structured films

“…In recent years, it is also frequently used for spintronics research; to observe domain wall motion in magnetic nanowires, to evaluate spin Hall effect in heavy metals, and to detect spin-orbit torque in magnetic layer/heavy metal layer heterostructures [10][11][12][13]. We can also evaluate the off-diagonal part of permittivity, which is the magneto-optical properties that determine the magnitude of the magneto-optical effect, from MOKE measurement [14][15][16][17][18][19]. In the study of the magneto-optical Kerr spectrum of Co/Pt multilayer films, it is often reported that a very large Kerr rotation angle can be obtained in the ultraviolet region.…”