Search Results (62)

Epitaxial thick films of yttrium iron garnet (YIG) are ideal for use in microwave devices due to their low losses at high frequencies. This report is on the growth of strain-engineered YIG films by liquid-phase epitaxy (LPE) on yttrium aluminum garnet (YAG) substrates with −3% lattice mismatch with YIG. Since the use of a lattice-matched substrate is preferred for LPE growths, a seed layer of YIG, 370–400 nm in thickness, was deposited by pulsed laser deposition (PLD) on (100), (110), and (111) YAG substrates. The seed layers were stoichiometric with magnetic parameters in agreement with the parameters for bulk single-crystal YIG and with strain-induced perpendicular magnetic anisotropy field H_a = 0.19–0.43 kOe. YIG films, 4 to 8.4 μm in thickness, were grown by LPE at 870 °C on YAG substrates with the seed layers using the PbO+B₂O₃ flux and annealed in air at 1000 °C. The films were Y-rich and Fe-deficient and confirmed to be epitaxial single crystals by X-ray diffraction. The saturation magnetization 4πM_s at room temperature was rather high and ranged from 1.9 kG to 2.3 kG. Ferromagnetic resonance at 5–15 GHz showed the absence of significant magneto-crystalline anisotropy in the LPE films with the line-width ΔH in the range 85–160 Oe, and H_a = 0.27–0.80 kOe which is much higher than for the seed layers. The high magnetization and H_a-values for the LPE films could be partially attributed to the off-stoichiometry. Although the strain due to the film–substrate lattice mismatch contributes to H_a, the mismatch in the thermal expansion coefficients for YIG and YAG is also a likely cause of H_a due to the high growth and annealing temperatures. The LPE-grown YIG films with high strain-induced anisotropy fields have the potential for use in self-biased microwave devices. Full article

Yttrium iron garnet (YIG), as a core material in microwave devices, remains a key focus in materials science for performance optimization. In this study, Y₃Fe_4.8Cu_0.1Sn_0.1O₁₂ samples were prepared via the solid-phase method with the co-doping of low-magnetic-anisotropy Cu²⁺ and Sn⁴⁺, combined with hot-press sintering under different conditions. Systematic analyses revealed that hot-press sintering optimized the microstructure, reduced porosity, and improved the compactness to 5.60 g/cm³. The sample hot-pressed sintered at 1200 °C achieved a maximum ε′ of 34, the lowest dielectric loss and a minimal FMR linewidth of 21 Oe, thus holding great potential for applications in high-frequency microwave devices requiring low loss and high integration. This work provides a viable approach to regulating the microstructure, dielectric properties, and magnetic properties of YIG ferrites. Full article

Spin transport behaviors in heavy metal/ferromagnetic insulator (HM/FI) bilayers have attracted considerable attention due to various novel phenomena and applications in spintronic devices. Herein, we investigate the planar Hall effect (PHE) in Pt/Tm₃Fe₅O₁₂ (Pt/TmIG) heterostructures at low temperatures; moment switching in the ferrimagnetic insulator TmIG is detected by using electrical measurements. Double switching hysteresis PHE curves are found in Pt/TmIG bilayers, closely related to the magnetic moment of Tm³⁺ ions, which makes a key contribution to the total magnetic moment of TmIG film at low temperature. More importantly, a magnetoresistance (MR) curve with double switching is found, which has not been reported in this simple HM/FI bilayer, and the sign of this MR effect is sensitive to the angle between the magnetic field and current directions. Our findings of these effects in this HM/rare earth iron garnet (HM/REIG) bilayer provide insights into tuning the spin transport properties of HM/REIG by changing the rare earth. Full article

Magneto-plasmonic structures have been a subject of tremendous attention of researchers in recent decades as they provide unique approaches regarding the efficient control of optical, magneto-optical, and nonlinear-optical effects. Among others, magneto-plasmonic crystals (MPCs) have become one of the most studied structures, known for their high-quality tunable resonant optical properties. Here, we present the results of experimental and numerical studies on the functional magneto-optical (MO) response of planar 1D plasmonic crystals composed of Co/Au stripes of submicron period on the surface of a 3 μm thick rare-earth garnet layer. The experimental and numerical studies confirm that the wavelength–angular spectra of such structures contain a set of tunable resonant features in their optical and magneto-optical response, associated with the excitation of (i) surface plasmon polaritons at the Co/Au grating–garnet interface, as well as (ii) waveguide (WG) modes propagating in the garnet slab. A comparison of the MO effects in the transversal and longitudinal magnetization of the plasmonic structures is presented. We show that the most efficient Fano-type MPC magneto-optical response is realized for the WG modes of the first order for the longitudinal magnetization of the structure. Further perspectives regarding the optimization of this type of plasmonic crystal are discussed. Full article

After reviewing the state of the art of the fluorination of inorganic solid electrolytes, an application of gas/solid fluorination is given and how it can be processed. Garnet-type oxide has been chosen. These oxides with an ideal structure of chemical formula A₃B₂(XO₄)₃ are mainly known for their magnetic and dielectric properties. Certain garnets may have a high enough Li⁺ ionic conductivity to be used as solid electrolyte of lithium ion battery. The surface of LLZO may be changed in contact with the moisture and CO₂ present in the atmosphere that results in a change of the conductivity at the interface of the solid. LiOH and/or lithium carbonate are formed at the surface of the garnet particles. In order to allow for handling and storage under normal conditions of this solid electrolyte, surface fluorination was performed using elemental fluorine. When controlled using mild conditions (temperature lower or equal to 200 °C, either in static or dynamic mode), the addition of fluorine atoms to LLZO with Li_6,4Al_0,2La₃Zr₂O₁₂ composition is limited to the surface, forming a covering layer of lithium fluoride LiF. The effect of the fluorination was evidenced by IR, Raman, and NMR spectroscopies. If present in the pristine LLZO powder, then the carbonate groups disappear. More interestingly, contrary to the pristine LLZO, the contents of these groups are drastically reduced even after storage in air up to 45 days when the powder is covered with the LiF layer. Surface fluorination could be applied to other solid electrolytes that are air sensitive. Full article

Thulium iron garnet (Tm₃Fe₅O₁₂, TmIG) is a promising material for next-generation spintronic and quantum technologies owing to its high Curie temperature and strong perpendicular magnetic anisotropy. However, conventional magnetometry techniques are limited by insufficient spatial resolution and sensitivity to probe local magnetic phase transitions and critical spin dynamics in thin films. In this study, we present the first quantitative investigation of local magnetic field fluctuations near the Curie temperature in TmIG thin films using nitrogen-vacancy (NV) center-based quantum sensing. By integrating optically detected magnetic resonance (ODMR) and NV spin relaxometry (T₁ measurements) with macroscopic techniques such as SQUID magnetometry and Hall effect measurements, we systematically characterize both the static magnetization and dynamic spin fluctuations across the magnetic phase transition. Our results reveal a pronounced enhancement in NV spin relaxation rates near 360 K, providing direct evidence of critical spin fluctuations at the nanoscale. This work highlights the unique advantages of NV quantum sensors for investigating dynamic critical phenomena in complex magnetic systems and establishes a versatile, multimodal framework for studying local phase transition kinetics in high-temperature magnetic insulators. Full article

The Mesoproterozoic (~1470 Ma) Wolf River batholith (WRB) is exposed over 6500 km², encompassing 11 plutons that crosscut the Archean Marshfield and Proterozoic Penokean terranes. As the WRB is the classically defined anorogenic batholith, to test this hypothesis, seven igneous phases were analyzed using anisotropy of magnetic susceptibility (AMS), as a proxy for magmatic flow during intrusion, and the samples recorded a sub-horizontal emplacement in six different orientations. Paleopoles from six of eight igneous samples preserve a wide variety of sub-vertical orientations with two reversed and four normal polarities. The synorogenic Baldwin Conglomerate is the youngest rock (<1460 Ga) associated with WRB. Magnetic fabrics are horizontal, but multidomain and paleopole signatures, where interpretable, are sub-vertical. The North American APWP places middle Laurentia at low-latitude during Geon 14, and all our paleopoles are sub-vertical, not sub-horizontal, again suggesting post-intrusion deformation. Moreover, the McCauley gneiss (1886 Ma; U-Pb zircon), Rib Mountain Quartzite (1750 Ma MDA; U-Pb zircon, n = 150), Dells of the Eau Claire rhyolite (1483 Ma; U-Pb zircon, 1469 Ma; monazites-in-garnet), and Baldwin conglomerate (1460 Ma MDA; U-Pb zircons, n = 150) are sub-vertical inliers (xenoliths) in the igneous suite; the Proterozoic Wausau turbidite (1850 Ma MDA; U-Pb zircon, n = 150) was intruded by the WRB and dips 25°W. Here, we present a reinterpretation of the WRB as a deformed synorogenic rather than an anorogenic intrusion. Full article

Thulium Iron Garnet (TIG), as an emerging hotspot in rare-earth iron garnet systems, possesses a large magnetostriction constant (λ₁₁₁) and a low damping coefficient. Therefore, it is possible to induce perpendicular magnetic anisotropy (PMA) through stress, which makes it more desirable for interfacial magnetic proximity or spin–orbit torque effects than Yttrium Iron Garnet (YIG). For achieving a high-quality TIG thin film and regulating its properties accordingly, understanding the effect of growth parameters on the film properties is essential. Using the Pulsed Laser Deposition (PLD) technique, we prepared TIG film on a Gadolinium Gallium Garnet (GGG) substrate. The correlations of its structural properties to the growth conditions are systematically studied, including the oxygen pressure and laser energy. With the annealing, a ferrimagnetic TIG thin film with PMA is successfully obtained. Our work provides a platform for achieving high-quality TIG thin films by experimentally regulating the growth factors. Full article

In this paper, we investigate the optical absorption and luminescence spectra of rare-earth garnets activated by the terbium (Tb³⁺) ion, as well as their magneto-optical properties. Crystals of terbium gallium garnet (TbGaG) and terbium aluminum garnet (TbAlG) are considered. The focus is on the physical and optical properties and structural features of the energy levels of rare-earth ions in the crystal field of garnets. This work highlights the importance of studying intraconfigurational 4f-4f and interconfigurational 4f-5d transitions, as well as the influence of the crystal field on the magnetic and optical properties of materials. Integrated methods are used, including absorption spectroscopy, luminescence and magneto-optical studies, which allows us to obtain detailed information on the excited states of rare-earth ions. The experimental results show the presence of significant Zeeman shifts, as well as anisotropy of the absorption and luminescence spectra, depending on the orientation of the crystal lattice and the external magnetic field. This work contributes to our understanding of the mechanisms of light absorption and emission in rare-earth garnets, which may facilitate the development of new optoelectronic devices based on them. Full article

The interaction between light and the magnetization of a material is called the magneto–optical effect. It was used in magneto–optical recording such as MO disks and has been applied to optical isolators etc. with the development of optical communications. The magneto–optical properties of magnetic garnets and their applications are briefly reviewed in this article. In the first half, after a brief overview of the phenomenology of the magneto–optical effect, the effects of element substitution on properties such as Faraday rotation and optical absorbance of magnetic garnets are shown. In the second half, some interesting applications such as imaging technologies and other novel applications using the magneto–optical effect of magnetic garnets are also introduced. Full article

Cancer is a major worldwide public health problem. Although there have already been astonishing advances in cancer diagnosis and treatment, the scientific community continues to make huge efforts to develop new methods to treat cancer. The main objective of this work is to prepare, using a green sol–gel method with coconut water powder (CWP), a new nanocomposite with a mixture of Gd₃Fe₅O₁₂ and ZnFe₂O₄, which has never been synthesized previously. Therefore, we carried out a structural (DTA-TG and X-ray diffraction), morphological (SEM), and magnetic (VSM and hyperthermia) characterization of the prepared samples. The prepared nanocomposite denoted a saturation magnetization of 11.56 emu/g at room temperature with a ferromagnetic behavior and with a specific absorption rate (SAR) value of 0.5 ± 0.2 (W/g). Regarding cytotoxicity, for concentrations < 10 mg/mL, it does not appear to be toxic. Although the obtained results were interesting, the high particle size was identified as a problem for the use of this nanocomposite. Full article

Garnet-type materials consisting of Y₃Al_5-2x(Mg,Ge)_xO₁₂ (x = 0, 1, 2), combined with Eu³⁺ or Ce³⁺ activator ions, were prepared by a solid-state method to determine the structural and optical correlations. The structure of Y₃Al_5-2x(Mg,Ge)_xO₁₂ (x = 1, 2) was determined to be a cubic unit cell (Ia-3d), which contains an 8-coordinated Y³⁺ site with octahedral (Mg,Al)O₆ and tetrahedral (Al,Ge)O₄ polyhedra, using synchrotron powder X-ray diffraction. When Eu³⁺ or Ce³⁺ ions were substituted for the Y³⁺ site in the Y₃Al_5-2x(Mg,Ge)_xO₁₂ host lattices, the emission spectra showed a decrease in the magnetic dipole f-f Eu³⁺ transition and a redshift of the d-f Ce³⁺ transition, related to centrosymmetry and crystal field splitting, respectively. These changes were monitored according to the increase in Mg²⁺ and Ge⁴⁺ contents. The dodecahedral and octahedral edge sharing was identified as a key distortion factor for the structure-correlated luminescence in the Eu³⁺/Ce³⁺-doped Y₃Al_5-2x(Mg,Ge)_xO₁₂ garnet phosphors. Full article

This investigation establishes an integrated method for rare earth elements (REE) exploration through a very promising and advanced exploration prospect in the Alces Lake area (SK, Canada) by assessing the integrated analysis of several multisource geophysical datasets. The resulting outcome provides important lithostructural information to the well-exposed, mineralized middle-to-lower crust at Alces Lake, comprising deep-seated poly-phase folds, ductile shear zones, and brittle faults. Geophysical–geological models of the Alces Lake property were constructed at different scales. The area of interest is located within the Beaverlodge Domain, about 28 km north of the Athabasca Basin’s northern margin. It contains some of the highest-grade rare earth elements (REE) in the world with the REE hosted predominantly in monazites within quartzo-feldspathic granitic to biotite–garnet–monazite–zircon-rich restite-bearing/cumulate mush melt pegmatites of anatectic origin (abyssal). Geophysical magnetic, gravity, and radiometric data were used together with Shuttle Radar Topography Mission (SRTM) images to facilitate the processing, modeling, and interpretation. Consequently, major structures were identified at different scales; however, the emphasis was given to studying those at the district/camp scale. The REE zones discovered to date occur within a large district-scale refolded synformal anticline. The eastern limb of this folded structure comprises a 30–40 km long, NW-trending shear zone/fault corridor with deep-seated structural crustal roots that may have served as the major pathway for ascending fluids/melts and facilitated the emplacement of mineralization. Thus, shear zones, faults, and folds in combination with lithological contacts/rheological contrasts appear to control residual/cumulate pegmatite emplacement and monazite deposition. Anomalies obtained from the airborne equivalent thorium survey data prove to be the most useful for REE pegmatite exploration. The results herein provide new interpretation and modeling perspectives leading to a better understanding of the distribution and lithostructural controls of REE on the property, and to new guidelines for future exploration programs at Alces Lake and elsewhere in northern Saskatchewan. Full article

Fe- and Al-rich metapelite from the Transangarian segment of the Yenisey Ridge (East Siberia, Russia) is a potential new source of high-alumina refractories. The rocks have relatively high average contents of Al₂O₃ (20 wt%) and Fe₂O₃ (7.91 wt%), moderate K₂O (3.44 wt%), and low CaO (0.74 wt%). Their dominant mineral assemblages are andalusite + muscovite + margarite + chlorite + biotite + quartz or staurolite + kyanite or/and andalusite + chlorite + muscovite + biotite + quartz with ±garnet and ±plagioclase. Al₂SiO₅ polymorphs occur as up to 1.5 cm andalusite porphyroblasts and partial or complete pseudomorphs after andalusite (kyanite and staurolite). Accessories include abundant Fe–Ti oxides and sporadic REE-, Y-, Ca-phosphates; sulfides are negligible. The composition of Al₂SiO₅ concentrates obtained in laboratory by heavy-media and magnetic separation from ≥0.06 mm fractions meet all requirements for raw material of this type: >56 wt% Al₂O₃, <42 wt% SiO₂, <1 wt% Fe₂O₃, <1.2 wt% TiO₂, and <0.2 wt% (CaO + MgO). The andalusite, kyanite, and mixed ores yield 0.7–4.1 wt%, 0.7–2.2 wt%, and 1.9–6.0 wt% of concentrate, respectively. The best-quality ores rich in Al₂SiO₅ polymorphs reside in zones of contact and/or dynamic metamorphism superimposed over regional metamorphism of Al-rich rocks. Full article

The study reports the influence of rare-earth ion doping on the structural, magnetic, and magnetocaloric properties of ferrimagnetic Gd_3−xRE_xFe₅O₁₂ (RE = Y, Nd, Sm, and Dy, x = 0.0, 0.25, 0.50, and 0.75) garnet compound prepared via facile autocombustion method followed by annealing in air. X-Ray diffraction (XRD) data analysis confirmed the presence of a single-phase garnet. The compound’s lattice parameters and cell volume varied according to differences in ionic radii of the doped rare-earth ions. The RE³⁺ substitution changed the site-to-site bond lengths and bond angles, affecting the magnetic interaction between site ions. Magnetization measurements for all RE³⁺-doped samples demonstrated paramagnetic behavior at room temperature and soft-ferrimagnetic behavior at 5 K. The isothermal magnetic entropy changes (−ΔS_M) were derived from the magnetic isotherm curves, M vs. T, in a field up to 3 T in the Gd_3−xRE_xFe₅O₁₂ sample. The maximum magnetic entropy change ($-∆S_M^{max}$) increased with Dy³⁺ and Sm³⁺substitution and decreased for Nd³⁺ and Y³⁺ substitution with x content. The Dy³⁺-doped Gd_2.25Dy_0.75Fe₅O₁₂ sample showed $-∆S_M^{max}$~2.03 Jkg⁻¹K⁻¹, which is ~7% higher than that of Gd₃Fe₅O₁₂ (1.91 Jkg⁻¹K⁻¹). A first-principal density function theory (DFT) technique was used to shed light on observed properties. The study shows that the magnetic moments of the doped rare-earths ions play a vital role in tuning the magnetocaloric properties of the garnet compound. Full article