Properties of Ferrite Garnet (Bi, Lu, Y)3(Fe, Ga)5O12 Thin Film Materials Prepared by RF Magnetron Sputtering

Abstract

This work is devoted to physical vapor deposition synthesis, and characterisation of bismuth and lutetium-substituted ferrite-garnet thin-film materials for magneto-optic (MO) applications. The properties of garnet thin films sputtered using a target of nominal composition type Bi0.9Lu1.85Y0.25Fe4.0Ga1O12 are studied. By measuring the optical transmission spectra at room temperature, the optical constants and the accurate film thicknesses can be evaluated using Swanepoel’s envelope method. The refractive index data are found to be matching very closely to these derived from Cauchy’s dispersion formula for the entire spectral range between 300 and 2500 nm. The optical absorption coefficient and the extinction coefficient data are studied for both the as-deposited and annealed garnet thin-film samples. A new approach is applied to accurately derive the optical constants data simultaneously with the physical layer thickness, using a combination approach employing custom-built spectrum-fitting software in conjunction with Swanepoel’s envelope method. MO properties, such as specific Faraday rotation, MO figure of merit and MO swing factor are also investigated for several annealed garnet-phase films.

Analysis, Optimization, and Characterization of Magnetic Photonic Crystal Structures and Thin-Film Material Layers

“…These data files still enable, in many cases, very reliable fitting of the physical thickness. It is highly recommended, then, to back up these thickness fitting results by also applying the Swanepoel method-based techniques, e.g., methods reported in [23].…”

“…In order to minimize errors, this combination of fitting procedures is only recommended if several deposited films of the same material are available which have a significantly different physical thickness, and the fitting procedures applied to more than one film consistently lead to obtaining well correlated datasets as a result of the absorption fitting. It is also recommended to apply the Swaneopol method-based fitting procedures [23], to reconfirm the validity and accuracy of the physical thickness data. Figure 8 illustrates the results of physical thickness and absorption fitting procedures obtained using a transmission file of a 481 nm thick Bi 0.9 Lu 1.85 Y 0.25 Fe 4.0 Ga 1 O 12 as-deposited film on a glass substrate, and the corresponding material's "zero-absorption" refractive index data file, both of which are included with program distribution in the corresponding subdirectories of the installation folder.…”

“…The present-day performance limits of 1D MPC in the visible spectral range have been evaluated using the same software [22] and using the available spectral data on the optical properties of the best-performing magnetic garnet compositions. Optical constants data of multiple recently-synthesized magnetic garnet compositions have been evaluated using the measured transmission spectra in conjunction with MPC Optimization software and Swanepoel envelope method [23]. Our group's preferred method for calibrating the quartz microbalance sensor's tooling factors of various deposition sources also involves fitting the actual film layer thickness using MPC Optimization software in conjunction with measured transmission spectra.…”

Analysis, Optimization, and Characterization of Magnetic Photonic Crystal Structures and Thin-film Material Layers

“…In order to minimize errors, this combination of fitting procedures is only recommended, if several deposited films of the same material are available, having a significantly different physical thickness, and the fitting procedures applied to more than one film consistently lead to obtaining wellcorrelated datasets as a result of absorption fitting. It is also recommended to apply Swaneopol method-based fitting procedures [23], to re-confirm the validity and accuracy of the physical thickness data. Figure 8 illustrates the results of physical thickness and absorption fitting procedures obtained using a transmission file of a 481 nm thick Bi0.9Lu1.85Y0.25Fe4.0Ga1O12 as-deposited film on a glass substrate, and the corresponding material's "zero-absorption" refractive index data file, both of which are included with program distribution into the corresponding subdirectories of the installation folder.…”

Terahertz response of gadolinium gallium garnet (GGG) and gadolinium scandium gallium garnet (SGGG)

“…As a substrate material, (S)GGG based heterostructures may find even more novel photonic applications. For example, alternating deposition of ultra-thin XIG and GGG films has led to the realization of all-garnet magnetooptical photonic crystals (MOPCs) [47][48][49][50][51][52][53][54][55][56][57][58][59][60][61]. Additionally, heterostructures combining (S)GGG-based garnet substrates and 2D quantum materials that exhibit giant Faraday rotations at THz frequencies [20,42,43] can potentially lead to broadband magneto-optical devices that cover the whole THz-tovisible frequency range.…”