Effect of substrate temperature on the magneto-optic properties of Bi1.8Lu1.2Fe3.6Al1.4O12 garnet films prepared by RF sputtering

In this paper we present a study conducted on RF sputtered garnet films of composition type Bi1.8Lu1.2Fe3.6Al1.4O12 prepared by using low and high substrate temperatures during the deposition process inside the vacuum chamber of sputtering system. Comparatively low coercive force is achieved in garnet films prepared at high substrate temperature of 680°C simultaneously with high MO quality and almost in-plane magnetization direction, which are the properties desired in various MO sensing, switching and imaging applications

Recent developments in solar energy-harvesting technologies for building integration and distributed energy generation

We present a review of the current state of the field for a rapidly evolving group of technologies related to solar energy harvesting in built environments. In particular, we focus on recent achievements in enabling the widespread distributed generation of electric energy assisted by energy capture in semi-transparent or even optically clear glazing systems and building wall areas. Whilst concentrating on recent cutting-edge results achieved in the integration of traditional photovoltaic device types into novel concentrator-type windows and glazings, we compare the main performance characteristics reported with these using more conventional (opaque or semi-transparent) solar cell technologies. A critical overview of the current status and future application potential of multiple existing and emergent energy harvesting technologies for building integration is provided

Initial field testing results from building-integrated solar energy harvesting windows installation in Perth, Australia

We report on the field testing datasets and performance evaluation results obtained from a commercial property-based visually-clear solar window installation site in Perth-Australia. This installation was fitted into a refurbished shopping center entrance porch and showcases the potential of glass curtain wall-based solar energy harvesting in built environments. In particular, we focus on photovoltaic (PV) performance characteristics such as the electric power output, specific yield, day-to-day consistency of peak output power, and the amounts of energy generated and stored daily. The dependencies of the generated electric power and stored energy on multiple environmental and geometric parameters are also studied. An overview of the current and future application potential of high-transparency, visually-clear solar window-based curtain wall installations suitable for practical building integration is provided

Bi-substituted ferrite garnet type magneto-optic materials studied at ESRI nano-fabrication laboratories, ECU, Australia

Since 2007, at the Electron Science Research Institute (ESRI) nano-fabrication laboratories, Edith Cowan University, Australia, we have devoted research efforts to the synthesis and characterization of bismuth-containing ferrite-garnet-type thin-film magneto-optic (MO) materials of different compositions. We report on the growth and characteristics of radio frequency (RF) magnetron sputtered bismuth-substituted iron-garnet thin films. We study the process parameters associated with the RF magnetron sputter deposition technique and investigate the results of optimizing process parameters. To achieve the best MO properties, we employ a few unique techniques, such as co-sputtered nanocomposite films and all-garnet multilayer structures, as well as the application of oxygen plasma treatment to amorphous garnet layers immediately following the deposition process. We demonstrated a remarkable enhancement in the MO properties of Bi-containing ferrite-type garnet thin-film materials, including record-high MO figures of merit and improved conventional and unconventional hysteresis loops of Faraday rotation. Previously unpublished research results on the forward-looking applications of magnetic garnet coatings applied to microparticles of advanced luminescent materials are reported. In the context of developing the next-generation ultra-fast optoelectronic devices, such as light intensity switches and modulators, high-speed flat panel displays, and high-sensitivity sensors, it is important to consider the desirable optical, magnetic, and magneto-optic properties that are found in highly bismuth-substituted iron garnet thin-film materials of various composition types

New Class of Garnet Nanocomposites for Use in Magnetic Photonic Crystals Prepared by RF Magnetron Co-sputtering

A new class of magneto-optic garnet nanocomposite materials is prepared using two Bi-substituted iron garnet materials of composition types (Bi,Dy) 3(Fe,Ga)5O12 and Bi3Fe 5O12. A composition adjustment approach is applied by varying the radio frequency (RF) powers driving each sputtering target during the deposition process. This new class of nanocomposite materials exhibits simultaneously high specific Faraday rotation, MO figure of merit, and effective uniaxial magnetic anisotropy after being crystallized through optimized annealing processes. We demonstrate experimentally that the excellent combination of materials\u27 properties obtained in this garnet nanocomposite is particularly advantageous for developing magneto-photonic crystals as well as optical sensors and isolators

Recent developments in magneto-optic garnet-type thin-film materials synthesis

Magneto-optic (MO) garnets are used in a range of applications in nanophotonics, integrated optics, communications and imaging. Bi-substituted iron garnets of different compositions are the most useful class of materials in applied magnetooptics due to their excellent MO properties (large Faraday effect) and record-high MO figure of merit among all semitransparent dielectrics. It is highly desirable to synthesise garnets which possess simultaneously a high MO figure of merit and large uniaxial magnetic anisotropy. However, the simultaneous optimization of several material properties and parameters can be difficult in single-layer garnet thin films, and it is also challenging to prepare films with high bismuth content using physical vapor deposition technologies. To meet the current challenge of developing next-generation functional MO materials, we design, develop and demonstrate the functionality of new magnetostatically-altered all-garnet multilayer heterostructures using two different garnet materials of dissimilar anisotropy types (out-of-plane and almost-inplane). The multilayer structures possess simultaneously a high MO figure of merit and large uniaxial magnetic anisotropy together with low coercivity, if each of the layers is optimized in composition and annealed correctly. We prepare thin-film heterostructures by sandwiching a MO garnet layer with almost in-plane magnetization in-between two MO garnet layers with out-of-plane magnetization using RF sputtering. We apply customised high-temperature oven annealing processes (optimized in temperature and process durations after running many trials) for the as-deposited (amorphous) garnet multilayers to obtain the crystalline garnet phase in every layer. These structures then possess simultaneously a high optical/MO quality and low coercivity, which is very attractive for the development of magnetic photonic crystals, sensing devices and ultra-fast switches. Based on Bi-substituted ferrite garnets grown on garnet substrates, this new and unique method for the development of new magnetic materials, enables customized magnetic properties to be attained, and can be used to develop novel types of synthetic garnet materials

High-Performance Thin-Film Garnet Materials for Magneto-Optic and Nanophotonic Applications

Since the 1960\u27s, Magneto-optic (MO) garnet materials have been studied extensively. These materials can possess world-record MO performance characteristics in terms of Faraday rotation and optical quality. Among the rear-earth-doped garnets, the Bi-substituted iron garnet is the best candidate for use as a functional material in different integrated-optics, imaging/image processing applications and also in forward-looking applications e.g. the design of metamaterials with non-reciprocal properties. We have established a set of technologies for fabricating ferrimagnetic garnet films of type (BiDy)3(FeGa)5O12 and also garnet-oxide nanocomposite (BiDy)3(FeGa)5O12 : Bi2O3 layers possessing record-high MO quality across the visible spectral range using RF-magnetron sputtering and oven annealing. Our MO garnet films possess excellent optical and magnetic properties, which make them very attractive and promising for a large range of optoelectronic, photonics-related and MO imaging applications

The properties of nanocomposite (BiDy)3(FeGa)5O12:Bi2O3 magneto-optic garnet films for applications in nanophotonics, ultrafast switching and integrated optoelectronics

We investigate the properties and applications of newly-developed RF-sputtered nano-composites with record-high magneto-optic quality (exceeding 25° at 532 nm and 42° at 635 nm). Bi-substituted dysprosium-gallium iron garnet layers with excess co-sputtered bismuth oxide content are demonstrated to possess very attractive optical and magnetic properties, which makes them suitable for novel magneto-optic and nanophotonic applications

Properties of ferrite garnet (bi, lu, Y)3(fe, ga)5O12 thin film materials prepared by RF magnetron sputtering

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 film

Garnet nanocomposite for use in magnetic photonic crystals prepared by composition adjustment in the Bi₃Fe₃O₁₂–Bi₂Dy₁Fe₄Ga₁ O₁₂ material system

RF co-sputtered nanocomposite (Bi3Fe5O12-Bi2Dy1Fe4Ga1O12) thin films are prepared using composition adjustment approach, implemented by varying the RF powers at each sputtering target. A new MO nanocomposite material is obtained by means of applying optimized annealing crystallization process to these as-deposited garnet layers. The optimally annealed garnet nanocomposites exhibit a significant red shift of the main MO transitions and show strong Faraday rotation of about 8.8°/μm at 532 nm simultaneously with having a high MO quality and magnetization direction perpendicular to the film plane