Viacheslav Kotov

RF magnetron sputtered (BiDy)3(FeGa)5O12:Bi2O3 composite garnet-oxide materials possessing record magneto-optic quality in the visible spectral region

Bismuth-substituted iron garnets are considered to be the most promising magneto-optical materials because of their excellent optical transparency and very high magneto-optical figures of merit in the near-infrared spectral region. However, the practical application of garnets in the visible and short-wavelength infrared parts of spectrum is currently limited, due to their very high optical absorption (especially in sputtered films) in these spectral regions. In this paper, we identify the likely source of excess absorption observed in sputtered garnet films in comparison with epitaxial layers and demonstrate (Bi,Dy)(3)(Fe,Ga)(5)O(12): Bi(2)O(3) composites possessing record MO quality in the visible region.

Highly bismuth-substituted, record-performance magneto-optic garnet materials with low coercivity for applications in integrated optics, photonic crystals, imaging and sensing

We report on the fabrication of radio frequency (RF) sputtered Bi-substituted lutetium iron garnet films doped with aluminum and the results of adjusting the properties of these films by means of co-sputtering deposition using an additional bismuth oxide target. Very attractive optical, magnetic and magneto-optical properties are achieved in these new magneto-optic materials. The high-performance magnetically-soft thin-film engineered materials synthesized have a wide range of potential applications in next-generation integrated optics, magneto-photonics and magnetic field sensors.

The Effect of Faraday Rotation Enhancement in Nanolayered Structures of Bi - substituted Iron Garnets

The effect of considerable enhancement of Faraday rotation (FR) and figure of merit (Q) in Bi, Gd, Al-substituted iron garnets plus Bi2O3 (Bi, Gd, Al: YIG / Bi2O3) nanocomposite films on Gd3Ga5O12 (GGG) substrates was found. It reached threefold enhancement of the FR and twofold of the Q one. These films were produced by reactive ion beam sputtering of appropriate targets and following separate annealing. In addition it was determined that in double layer Bi-substituted yttrium iron garnet (Bi: YIG) nanostructures on GGG substrates the upper layer (0.5 – 3.0 nm) considerably affects the magneto-optical properties of the “thick” (8.0 – 10.0 nm) bottom layer. The possible reasons of these effects are discussed.

Garnet multilayer thin film structure with magnetostatically-altered and improved magnetic properties prepared by RF magnetron sputtering

We prepare an all-garnet multilayer film structure by sandwiching a magneto-soft garnet material in between two magneto-hard garnet materials with high bismuth substitution levels using RF magnetron sputtering technique and investigate the microstructure and the effects of magnetostatic inter-layer coupling on magnetic properties. Both types of the Bi-substituted magneto-optic garnet materials used possess excellent optical, magnetic and magneto-optical properties suitable for the application in different new and emerging technologies in optics and photonics. Garnet layers of composition type Bi2Dy1Fe4Ga1O12 have strong perpendicular magnetic anisotropy and Bi1.8Lu1.2Fe3.6Al1.4O12 magneto-soft layer features magnetization behavior similar to that of in-plane magnetized films. The all-garnet magnetostatically-coupled multilayer structure fabricated demonstrates an attractive combination of low coercive force and high uniaxial magnetic anisotropy, which is extremely useful for applications in nanophotonics, optical sensors and isolators.

Nanostructured Engineered Materials With High Magneto-Optic Performance for Integrated Photonics Applications

In this paper, we experimentally investigate the performance of a set of technologies used for the deposition, annealing and characterization of high-performance magnetooptic rare-earth-doped garnet materials and all-garnet heterostructures for use in photonic crystals and novel integrated-optics devices.

Properties of Exchange Coupled All-garnet Magneto-Optic Thin Film Multilayer Structures

The effects of exchange coupling on magnetic switching properties of all-garnet multilayer thin film structures are investigated. All-garnet structures are fabricated by sandwiching a magneto-soft material of composition type Bi1.8Lu1.2Fe3.6Al1.4O12 or Bi3Fe5O12:Dy2O3 in between two magneto-hard garnet material layers of composition type Bi2Dy1Fe4Ga1O12 or Bi2Dy1Fe4Ga1O12:Bi2O3. The fabricated RF magnetron sputtered exchange-coupled all-garnet multilayers demonstrate a very attractive combination of magnetic properties, and are of interest for emerging applications in optical sensors and isolators, ultrafast nanophotonics and magneto-plasmonics. An unconventional type of magnetic hysteresis behavior not observed previously in magnetic garnet thin films is reported and discussed.

YIG: Bi2O3 Nanocomposite Thin Films for Magnetooptic and Microwave Applications

Y3Fe5O12-Bi2O3 composite thin films are deposited onto Gd3Ga5O12 (GGG) substrates and their annealing crystallization regimes are optimized (in terms of both process temperatures and durations) to obtain high-quality thin film layers possessing magnetic properties attractive for a range of technological applications. The amount of bismuth oxide content introduced into these nanocomposite-type films is controlled by adjusting the RF power densities applied to both Y3Fe5O12 and Bi2O3 sputtering targets during the cosputtering deposition processes. The measured material properties of oven-annealed YIG-Bi2O3 films indicate that cosputtering of YIG-Bi2O3 composites can provide the flexibility of application-specific YIG layers fabrication of interest for several existing, emerging, and also frontier technologies. Experimental results demonstrate large specific Faraday rotation (of more than 1°/µm at 532 nm), achieved simultaneously with low optical losses in the visible range and very narrow peak-to-peak ferromagnetic resonance linewidth of around Δ= 6.1 Oe at 9.77 GHz.

Physical Properties and Behaviour of Highly Bi-Substituted Magneto-Optic Garnets for Applications in Integrated Optics and Photonics

Rare-earth and Bi-substituted iron garnet thin film materials exhibit strong potential for application in various fields of science and frontier optical technologies. Bi-substituted iron garnets possess extraordinary optical and MO properties and are still considered as the best MO functional materials for various emerging integrated optics and photonics applications. However, these MO garnet materials are rarely seen in practical photonics use due to their high optical losses in the visible spectral region. In this paper, we report on the physical properties and magneto-optic behaviour of high-performance RF sputtered highly bismuth-substituted iron garnet and garnet-oxide nanocomposite films of generic composition type (Bi, Dy/Lu)3(Fe, Ga/Al)5O12. Our newly synthesized garnet materials form high-quality nanocrystalline thin film layers which demonstrate excellent optical and MO properties suitable for a wide range of applications in integrated optics and photonics.

High-quality RF-sputtered magneto-optic garnet films of Bi 1.8 Lu 1.2 Fe 3.6 Al 1.4 O 12 with low coercivity for applications in integrated optics, imaging and sensing devices

In this paper, we report on the fabrication of RF sputtered Bi-substituted lutetium iron garnet films doped with aluminum and featuring in-plane easy magnetization axis orientation as well as very attractive optical, magnetic and magneto-optical properties (MO figure of merit exceeding 15° at 635 nm, coercivity below 50 Oe and Faraday-effect magnetic field sensitivity up to 157 °/(cm·Oe) at 532 nm). These magnetically-soft thin-film engineered materials have a wide range of potential applications in next-generation integrated optics, magnetophotonics and magnetic field sensors.

Synthesis of high-performance magnetic garnet materials and garnet-bismuth oxide nanocomposites using physical vapor deposition followed by high-temperature crystallization

Bi-substituted iron garnet (Bi:IG) compounds synthesized in thin film form are the best semi-transparent magneto-optical (MO) materials for applications in magnetic recording, optical sensors, and photonics. These materials can possess attractive magnetic properties and the highest specific Faraday rotation in the visible and near-infrared spectral regions, if the deposited layers contain a high volumetric fraction of the garnet phase and possess high-quality surfaces and microstructure. In this paper, we study the effects of various deposition and annealing process parameters on the properties of Bi:IG and garnet-oxide nanocomposite films of several composition types fabricated using radio-frequency (RF) sputtering deposition followed by high-temperature isothermal crystallization. We also investigate the kinetics of garnet phase formation within a garnet-Bi-oxide nanocomposite material.