Magneto-optical Characteristics Research Articles

Transparent Tb2Ti2O7 ceramics for use in Faraday isolators

Magneto-optical and thermo-optical characteristics of transparent Tb2Ti2O7 ceramics were investigated. The dependence of the index of refraction on the wavelength in the 0.29–2 μm range, the wavelength and temperature dependence of the Verdet constant, as well as the dependence of thermally induced depolarization on laser radiation power were measured. The value of the Verdet constant in Tb2Ti2O7 surpasses that in Tb3Ga5O12 by more than 1.68 times. The thermo-optical characteristic Qeff was estimated to be (1.8–3.7)∙10−8 1/K, which is record small compared to Qeff of the known magneto-optical materials. The small value of Qeff makes Tb2Ti2O7 a highly promising magneto-optical material for Faraday isolators and rotators for high average power lasers.

Magneto-optical Properties of Iron-bulk Metallic Glasses Sustainably Produced from Iron-rich Sand Sludge

A large amount of sand sludge (SS) from rivers polluted with heavy metals is continuously dredged and often dumped into landfills, resulting in environmental pollution of soil and water. This work examines the feasibility of the utilization of iron-enriched SS from dredged polluted rivers to produce Fe-based bulk metallic glasses (Fe-BMG). Fe-BMG was prepared from SS by melt-quenching technique, and their magnetic and photochromic properties were studied. The chemical composition of the Fe-BMG was determined by X-ray fluorescence (XRF). The structural properties have been analyzed using the Raman spectroscopy (RS), vibrating sample magnetometer (VSM) and ultraviolet-visible (UV-VIS) spectroscopy. XRF results shows that Fe-BMG contains an iron proportion of 38.8% (wt.) as the hematite (\(\alpha\)-Fe2O3), and magnetite (Fe3O4) phases. The Raman “fingerprints” of \(\alpha\)-Fe2O3 and Fe3O4 were identified at 1330 cm−1, and 300-600 cm-1, respectively. The measured saturation magnetization of Fe-BMG samples is 3.0 emu/g at 60 kOe. A UV-VIS analysis of the Fe-BMG exposed to sunlight simulator reveals an enhanced transmission of light in the 400-700 cm-1 region. These findings confirmed the successful conversion of the hazardous SS into Fe-BMG with promising magneto-optical characteristics for a wide variety of technological applications.

Robust half-metallic ferromagnet in doped double perovskite Sr2TiCoO6 by rare-earth elements for photovoltaic and thermoelectric conversion: A DFT method

In this study, we have discovered a novel candidate series of half-metals by replacement of the Ti atom with the rare-earth elements RE (=Dy, Ho, Er, or Tm) in the double perovskite Sr2TiCoO6. We methodically investigated the electronic, magneto-optical, and thermoelectric characteristics of the compounds Sr2(RE)CoO6 using the FP-LAPW method. The spin-polarized electronic structure studied within GGA-WC and GGA + U showed a robust half-metallic character for all compounds. The substitution by the rare-earth elements RE enhanced the magnetic characteristics of Sr2TiCoO6, which exhibits a transition from a total magnetic moment of 1μB for Sr2TiCoO6 to 7μB, 6μB, 5μB, and 4μB for Sr2DyCoO6, Sr2HoCoO6, Sr2ErCoO6, and Sr2TmCoO6, respectively. However, the hybridization between RE-4f, Co-3d, and O-2p is responsible for robust half-metallic ferromagnet in Sr2(RE)CoO6 compounds. We have also studied the effect of spin-orbit coupling (SOC) on electronic structure. The Sr2DyCoO6, Sr2HoCoO6, and Sr2ErCoO6 compounds maintained their half-metallicity under GGA + SOC, whereas Sr2TmCoO6 became a magnetic metal. An in-depth analysis of the optical and thermoelectric characteristics was performed by GGA + U. According to the absorption coefficient and imaginary part of the dielectric function, we have found that the compounds Sr2(RE)CoO6 have better absorption quantities at different frequencies (IR, visible, and UV) than Sr2TiCoO6. Due to their high ZT and good Seebeck coefficient in a spin-up canal, the investigated compounds have excellent thermoelectric efficiency. These characteristics make the double perovskites Sr2(RE)CoO6 as a high absorber an attractive choice for photovoltaic solar cells and thermoelectric applications.

Ultrasensitive magnetic field sensor based on cladding-etched long-period grating.

We demonstrate a high-sensitivity fiber-optic magnetic field sensor, which consists of a cladding-etched long-period fiber grating (LPFG) near the dispersion turning point (DTP) integrated with a magnetic fluid (MF). By reducing the cladding diameter of the LPFG, the fundamental mode is coupled to the lowest order cladding mode (LP0,2) near the DTP, which has a much higher surrounding refractive index sensitivity. Thanks to the excellent magneto-optical characteristics of the MF, the proposed sensor can achieve a magnetic field intensity sensitivity of 44.69 nm/mT in the range of 3-7.4 mT. The minimum magnetic field intensity that can be detected is 0.45 µT due to the 0.02-nm wavelength resolution of the optical spectrum analyzer. The proposed etched DTP-LPFG-based sensor with ultrahigh magnetic field sensitivity could have potential applications in magnetic fields and electrical systems.

Polarization and magneto-optical characteristics of Tb:YAG crystal-derived silica fiber via laser-heating drawing technique

Polarization and magneto-optical characteristics of Tb:YAG crystal-derived silica fiber via laser-heating drawing technique

First-principles assessments of the electronic, and magneto-optical characteristics of Fe–Mn co-doped anatase TiO2 for photo-catalysis applications

First principles modeling is conducted to scrutinize the structural, chemical, electronic structures, bonding character, and magneto-optical features of intrinsic or pure anatase TiO2, Fe or Mn single-atom doped, and Mn–Fe diatom co-doped anatase TiO2 systems, respectively. Herein, the spin-polarized density functional theory (DFT) concerted with the on-site Hubbard (U) correction scheme for the Coulomb interaction, is utilized for the exchange-correlation term, as the generalized gradient approximation (GGA)+U. The spin-polarized density of states of Mn mono-atom doped anatase TiO2 material indicated a magnetic semiconductor attribute for both down/up spin components. Conversely, the outcome spin-polarized density of states of both Fe-doped and Mn–Fe co-doped anatase TiO2 materials illustrated the emergence of an intermediate band behavior. Accordingly, three magnetic impurity bands are produced in Mn–Fe co-doped anatase TiO2, the first two spin-up bands are located just uppermost the valence states nearby the Fermi level and the third spin-up/down band is lying far from the Fermi level just below the minimum conduction band. Interestingly, the spin-polarized charge density displayed an orbital ordering between the O 2p-orbitals and 3d-orbitals of Mn–Fe doped diatoms in the host TiO2 anatase system. The valuable optical ingredients, such as the optical absorption coefficient, refractive index, reflectivity spectra, optical conductivity, and electron energy loss function, are inspected and discussed. Moreover, the optical absorption coefficient characteristics of the mono-doped Mn/Fe and Mn–Fe co-doped TiO2 anatase structure displayed a relocation in the absorption feature edges towards the visible electromagnetic radiation regime. This means that the induced impurity bands delineate the essential contributor for boosting the catalytic activity in the visible light. It is expected that the Fe–Mn co-doped anatase TiO2 system could be a compelling candidate for its ultimate use in the photo-catalysts or magnetic storage devices.

Probing into the physicochemical consequences of pristine and X0.06Ni0.94O (X = Co, Fe, Cu) nanoparticles for bactericidal, antifungal and hemolytic competency

Nano-scaled transition metal oxides are massively gaining an exciting horizon of research interest among material scientists by triggering scientific attention due to its prime advancements in physico-chemical, magneto-optical, electro-chemical, bio-medical and bio-compatible characteristics. The current work highlights the fabrication and formalisation of pure and X0.06Ni0.94O (X = Co, Fe, Cu) nanoparticles via bottom-up sol-gel pathway employing citric acid as the gelling factor. The crystallite size evaluated from X-Ray Diffraction (XRD) analysis decreased with respect to doping were estimated by successive systems among which Halder-Wagner (H-W) and Wagner-Agua (W-A) approach delivered prime results. Fourier Transform Infra-Red (FTIR) spectroscopy analysis regulated at room temperature in the mid infrared frequency continuum 400–4000 cm−1 confirmed the cubic conformation and the presence of predicted functional groups in the as-synthesized nanoparticles. The bandgap energy calculated from Ultra Violet-visible (UV–vis) spectroscopy is found to decrease for Co-NiO and Cu-NiO nanoparticles and increased for Fe doped NiO nanoparticles in comparison with the bandgap of pure NPs reasoned out by the Burstein-Moss shift. The device dependent parameter Urbach energy, and other pivotal optical parameters crucial in the fabrication of optoelectronic devices were evaluated. Surface morphological features and porous network of doped nanoparticles were investigated from Scanning Electron Microscopy (SEM) technique. Energy Dispersive X-ray (EDX) spectra ascertained the molecular matrix array and elemental composition in synthesized samples. The surface area measured from Brunauer-Emmett-Teller (BET) analysis revealed higher surface area (42 m2/g) for Fe-doped NiO nanoparticles than other counterparts. The thermal decomposition and stability of the pure and doped samples were analysed by Thermo-Gravimetric (TG) studies. The fundamental kinetic and thermodynamic parameters such as entropy, enthalpy, activation and Gibb’s free energy were elucidated through six different models viz., Coats-Redfern (CR), Piloyan-Novikava (PN), Horowitz-Metzger (HM), Van-Krevelen (VK), MacCallum-Tanner (MT) and Broido methods. Vibrating Sample Magnetometer (VSM) analysis coupled with the Law of Approach to Saturation (LAS) operandi extracted two critical magnetic criteria and the saturation magnetization is noticed to reduce with doping. The antibacterial and antifungal efficacies of the as-synthesized NPs were deeply discussed by portraying the nanoparticles-microbes interface. Iron and copper doped nickel oxide nanoparticles encountered favorable antimicrobial activity against pathogenic organisms. Furthermore, the bio-compatibility nature of the NPs was examined through hemolytic activity and the samples exhibited non-toxic behavior towards human cells till 50 μg/ml.

Tb3+ Ion Optical and Magneto-Optical Properties in the Cubic Crystals KTb3F10.

The optical and magneto-optical characteristics of KTb3F10 crystals in the transition region of 5D4 → 7F6 4f8 configurations of the Tb3+ ion at temperatures of 90 and 300 K were studied. The schemes of the optical transitions in the KTb3F10 crystals were constructed, and the energies of most of the Stark sublevels of the ground 7F6 and excited 5D4 multiplets of the Tb3+ ion split by the C4v symmetry crystal environment were determined. The presence of three- and two-doublet states in the energy spectra of the Tb3+ion multiplets 7F6 and 5D4, respectively, was established, which is in good agreement with theoretical predictions. The use of the wavefunctions of the Stark sublevels of multiplets split by a tetragonal crystal field and combining in the studied optical transition made it possible to explain some of the magnetic and magneto-optical features observed in the KTb3F10 single crystals.

Investigation of Magnetic and Photocatalytic Properties of CoFe2O4 Doped La3+, Nd3+, I3+

Cobalt ferrites are widely used for permanent magnets, magnetic fluids, microwave devices, high density information storage and environmental technologies. The properties of nanosized magnetic materials strongly depend on the shape, size, and phase composition of the particles. The great interest of researchers in nanosized materials in recent years is associated with the possibility of changing the properties of magnetic materials by controlling the particle size and distribution of cations over sublattices in ferrite [1].Nanoparticles of doped cobalt ferrite showed improved physicochemical characteristics compared to individual components due to the synergistic effect of the mutual presence of cations. Currently, various technologies for producing ferrites are used. However, to obtain a single-phase product, calcination of the precursors at a temperature of 1300-1500 0C is required, which causes agglomeration and sintering of the product. The use of modern methods of electrochemical synthesis is the basis for obtaining ferrites from transition materials with a given set of properties. A characteristic recent trend is the development of new technologies and compositions for the production of precisely nanodispersed ferrites [2].The purpose of this work is to study the possibility of using contact low-temperature nonequilibrium plasma for the synthesis of cobalt ferrites doped with La3+, Nd3+, I3+ cations, to establish a relationship between the cationic composition of ferrites and its phase composition, magnetic and structural characteristics.Ferrites were synthesized in the form of nanoparticles using contact nonequilibrium low temperature plasma in an electrochemical reactor. The crystalline microstructure of the samples was revealed by X-ray diffraction and X-ray phase methods. The magnetic characteristics were determined from hysteresis loops. The EPR spectra were obtained on a Radiopan SE/X-2543 radiospectrometer. To characterize the EPR signals, the intensity and width of the signal, and the resonant frequency were used. The visualization of the dependences of the technological characteristics of La3+-Nd3+-I3+ ferrites on the cationic composition was carried out by the simplex method using the STATISTICA 12 program.It has been established that the nature of the rare-earth metal cation in cobalt ferrite directly determines the magnetic and photocatalytic properties of spinel ferrites. The effect of the mutual influence of the content of cations on the saturation magnetization and coercive force is determined. The most influencing factor is the content of neodymium cations. Low values of the coercive force for Mn-Zn and Co-Zn ferrites and high values for the entire range of Co-Mn ferrites are established. An increase in the content of cobalt cations leads to an increase in the saturation magnetization value of Co-Mn ferrites. The EPR spectra show that the values of the resonance field and linewidth in the EPR spectrum correlate with the value of magnetic saturation.Simultaneous substitution of Nd3+ and La3+ in CoFe2O4 nanoparticles affected the structure, magnetic and photocatalytic properties. Structural parameters were investigated and calculated using X-ray diffraction studies. The magnetization analyzes were carried out at room temperature. Various magnetic parameters have been obtained and discussed, including remanence (Mr), coercive force (Hc), saturation magnetization (Ms), squareness ratio (SQR=Mr/Ms) and magnetic moment (nB). An increase in Mr, Ms, Hc and nB was found at lower concentrations of Nd3+ and La3+. An increase in the content of Nd3+ cations leads to a significant increase in the coercive force. The analysis of photocatalytic activity in the reaction of isolation of furacilin showed the best results (destruction rate 98%, time 40 minutes) for the ternary composition.References Caldeira, Luis Eduardo, et al. "Correlation of synthesis parameters to the structural and magnetic properties of spinel cobalt ferrites (CoFe2O4)–an experimental and statistical study." Journal of Magnetism and Magnetic Materials550 (2022): 169128.Lu, Yuzheng, et al. "Effect of Gd and Co contents on the microstructural, magneto-optical and electrical characteristics of cobalt ferrite (CoFe2O4) nanoparticles." Ceramics International2 (2022): 2782-2792.

Effect of Gd and Co contents on the microstructural, magneto-optical and electrical characteristics of cobalt ferrite (CoFe2O4) nanoparticles

Rare earth oxides with a trivalent nature play a pivotal role in reinforcing the magneto-optical attributes of spinel ferrite nanoparticles by replacing Fe 3+ ions. In this study, rare earth Gd oxide doped with CoFe 2 O 4 NPs with a composition of Co 1+x Gd x Fe 2-2x O 4 (x = 0, 0.05, 0.10, and 0.15) were synthesized using sol-gel auto-combustion. The outcome of Gd cations on the physical, magneto-optical and electrical characteristics of the cobalt ferrite NPs were reported. X-ray diffraction (XRD), and Fourier transform infrared (FTIR) investigations confirmed the single-phase cubic crystalline nature and metal ion stretching in the cobalt ferrite synthesized samples. Decreasing drift in the average crystallite and grain sizes (estimated from the XRD patterns and SEM micrographs) and magnetic saturation ( M s ) were examined with the increasing content of Gd oxide and Co ions in the CoFe 2 O 4 NPs. The optical bandgap of the synthesized samples explains the semiconducting nature of the prepared NPs due to the presence of an E g from 2.13 eV to 2.45 eV in the semiconductor region. The electrical properties of the co-doped samples exhibit a conducting trend in the presence of Gd 3+ ions with the increase of temperature from 298 K to 973 K. DC measurements of the synthesized NPs demonstrated DC conductivity values from 0.1087 S/cm to 0.2676 S/cm at 973 K. The room temperature magnetic analysis of Gd and Co doped Cobalt Ferrite (CoFe 2 O 4 ) NPs using vibrating sample magnetometer; DC conductivity Gd and Co doped Cobalt Ferrite (CoFe 2 O 4 ) NPs from 298 K to 973 K.

Spectroscopic and magneto-optical characteristics of erbium doped cerium trifluoride crystal grown by the Bridgman method

In this study, a 2 at% erbium doped cerium trifluoride (Er:CeF3) single crystal was grown using the Bridgman method. The consequent absorption, infrared transmittance, and fluorescence spectra were recorded. The spectroscopic properties of Er:CeF3 crystals were intensively studied based on the Judd–Ofelt (J–O) theory. The Ω2, Ω4, and Ω6 parameters were fitted to be 5.206 × 10−20, 1.805 × 10−20, and 3.06 × 10−20 cm2, respectively. The emission cross-section centered at 1564.6 nm was calculated to be 1.053 × 10−20 cm2, and the corresponding fluorescence lifetime was measured to be 1.675 ms. Additionally, the magneto-optical (MO) performance of the Er:CeF3 crystal was investigated for the first time. The Verdet constants of Er:CeF3 at 532, 632.8, 1064, and 1310 nm are 231.0, 165.4, 43.4, and 24.4 rad·T−1·m−1, respectively, which are significantly higher than those of pure CeF3 and traditional Tb3Ga5O12. The results show that the Er:CeF3 crystal can be applied both to solid-state lasers and Faraday devices.

Tunable magneto-optical and interfacial defects of Nd and Cr-doped bismuth ferrite nanoparticles for microwave absorber applications

Tunable microwave absorption characteristics are highly desirable for industrial applications such as antenna, absorber, and biomedical diagnostics. Here, we report BiNdxCrxFe1-2xO3 (x = 0, 0.05, 0.10, 0.15) nanoparticles (NPs) with electromagnetic matching, which exhibit tunable magneto-optical and feasible microwave absorption characteristics for microwave absorber applications. The experimental results and theoretical calculations demonstrate the original bismuth ferrite (BFO) crystal structure, while Nd and Cr injection in the BFO structure may cause to minimize dielectric losses and enhance magnetization by producing interfacial defects in the spinel structure. Nd and Cr co-doping plays a key role in ordering the BFO crystal structure, resulting in improved microwave absorption characteristics. The BiNd0.10Cr0.10Fe1.8O3 (BNCF2) sample exhibits a remarkable reflection loss (RL) of −37.7 dB with a 3-mm thickness in the 10.15 GHz-10.30 GHz frequency region. Therefore, Nd and Cr doping in BFO nanoparticles opens a new pathway to construct highly efficient BFO-based materials for tunable frequency, stealth, and microwave absorber applications.

Exploring the structural, elastic, optical, dielectric and magnetic characteristics of Ca2+ incorporated superparamagnetic Zn0.5−xCa0.1Co0.4+xFe2O4 (x = 0.0, 0.05 & 0.1) nanoferrites

This work is aimed to understand influence of 10% Ca doping on the structural, optical, dielectric and magnetic behavior of half doped Zinc-Cobalt nanoferrites. Zn0.5−xCa0.1Co0.4+xFe2O4 (x = 0.0, 0.05 & 0.1) nanoferrites with crystallite size in 10–13 nm range were synthesized through a sol-gel auto-incinerated route. Rietveld profile refinement of PXRD patterns, observation of spinel ferrite type fcc Laue rings in SAED patterns, Raman modes (A1g,T2g & Eg) and metal-oxide (υ1 & υ2) bonds in 400–600 cm−1 IR range illustrated formation of single phase mixed valent spinel type fcc nanoferrites. In these nanoferrites Zn2+ ion resides at tetrahedral (TA) site, while Co2+ & Ca2+ ions preferentially fill the octahedral OB site and Fe3+ ion occupy both TA & OB sites. Moderate optical absorbance in blue color region and strong absorbance in the lower UV region is observed in these nanoferrites, which is owing to presence of mixed valent ions at the OB and TA sites respectively. 10% Ca doping in these half doped Zn-Co nanoferrites led to considerable decrement in the band gap energy (Eg) and turning them to semiconducting state (Eg in 2.5–2.3 eV range). In these nanoferrites hopping of electrons between divalent Fe2+, Ca2+, Zn2+, Co2+ & trivalent Fe3+ & Co3+ cations led to systematic decrease in the dielectric parameters with frequency. These nanoferrites exhibited superparamagnetism with a high magnetic moment (~ 2.9–3.0μB/f.u.) at room temperature. Systematic enhancements in saturation magnetization (Ms), coercivity (Hc), remanence (Mr) and squareness ratio at low temperatures revealed changing of superparamagnetic character to soft ferrimagnetic state of these nanoferrites. At 20K, highest value of Ms = 119 emu/g was observed for Zn0.5Ca0.1Co0.4Fe2O4 nanoferrite, while highest Hc = 2911 Oe & Mr = 61.0 emu/g were recorded for Zn0.4Ca0.1Co0.5Fe2O4 nanoferrite. Thus, a moderate 10% Ca2+ ion incorporation in Zn0.5−xCa0.1Co0.4+xFe2O4 (x = 0.0, 0.05 & 0.1) nanoferrites is emerged as an effective route for obtaining superparamagnetic nanoferrites with high magnetic moment and reduced band gap energy. Unique magneto-optical characteristics of Zn0.5−xCa0.1Co0.4+xFe2O4 (x = 0.0, 0.05 & 0.1) nanoferrites would project them as a good material for opto-magnetic, drug carrier, biomedical contrast agent and magnetic storage applications.

Two-Dimensional Chromium Bismuthate: A Room-Temperature Ising Ferromagnet with Tunable Magneto-Optical Response

We present a density functional theory (DFT) based study of a two-dimensional phase of chromium bismuthate (CrBi), previously unknown material with exceptional magnetic and magnetooptical characteristics. Monolayer CrBi is a ferromagnetic metal with strong spin-orbit coupling induced by the heavy bismuth atoms, resulting in a strongly anisotropic Ising-type magnetic ordering with the Curie temperature estimated to be higher than 300 K. The electronic structure of the system is topologically nontrivial, giving rise to a nonzero Berry curvature in the ground magnetic state, leading to the anomalous Hall effect with the conductivity plateau of $\sim$1.5 $e^2/h$ at the Fermi level. Remarkably, the Hall conductivity and the magnetooptical constant are found to be strongly dependent on the direction of magnetization. Besides, monolayer CrBi demonstrates the polar magnetooptical Kerr effect in the visible and near-ultraviolet spectral ranges with the maximum rotation angles of up to 10 mrad. Our findinds suggest that monolayer CrBi is a promising system for practical applications in magnetooptical and spintronic devices.

Tunable and asymmetric optical bistability of one-dimensional photonic crystals based on InSb and nonlinear materials.

In this paper, one-dimensional (1D) photonic crystals (PCs) based on InSb and nonlinear materials are studied using the transmission matrix method. It is found that in the terahertz band, due to the magneto-optical characteristics of InSb, when the incident light propagates through such 1D PCs in two different directions (forward and backward propagation), an asymmetric optical bistable state can be obtained. Propagating from the forward direction, the bistable state is achieved. Spreading from the backward direction, the multistable state can be observed. Compared with the bistable threshold value for the case of forward incidence, the similar value that appeared in the multistable curve is significantly reduced. The polarization-sensitive features of the asymmetric optical bistability of the presented 1D PCs are also investigated under TM waves, which focuses on the tuning effects of incident angle, external magnetic field, temperature, and the thicknesses of the InSb and nonlinear dielectric layers on the asymmetric optical bistability. The results show that when the incident light enters from two different directions, the tailoring effects of the incident angle and thickness of the InSb layer on the bistable state are obviously different, but the tuning influences of the magnetic field, temperature, and the thickness of the nonlinear material layer on the bistable state are similar. The asymmetric optical bistability we made in this paper can be applied to multifunctional devices and nonreciprocal optical isolators.

A New Zinc Phosphate-Tellurite Glass for Magneto-Optical Applications.

This work investigates the structural, magnetic and magneto-optical properties of a new zinc phosphate-tellurite glass belonging to the 45ZnO-10Al2O3-40P2O5-5TeO2 system. The glass was prepared by a wet method of processing the starting reagents followed by suitable melting–stirring–quenching–annealing steps. Specific parameters such as density, average molecular mass, molar volume, oxygen packaging density, refractive index, molar refractivity, electronic polarizability, reflection loss, optical transmission, band gap and optical basicity have been reported together with thermal, magnetic and magneto-optical characteristics. Absorption bands appear in the blue and red visible region, while over 600 nm the glass becomes more transparent. FTIR and Raman spectra evidenced phosphate-tellurite vibration modes proving the P2O5 and TeO2 network forming role. Magnetic measurements reveal the diamagnetic character of the Te-doped glass with an additional weak ferromagnetic signal, specific to diluted ferromagnetic oxides. Positive Faraday rotation angle with monotonous decreasing value at increasing wavelength was evidenced from magneto-optical measurements. The final product is a composite material comprising of a non-crystalline vitreous phase and Te-based nanoclusters accompanied by oxygen vacancies. The metallic-like Te colloids are responsible for the dark reddish color of the glass whereas the accompanying oxygen vacancies might be responsible for the weak ferromagnetic signal persisting up to room temperature.

Reflectance and magneto-optical Kerr rotation of Graphene/SiC/InSb/SiC/Al structure at terahertz frequency region

In this paper, a numerical study on the reflectance and Kerr rotation spectra of a multilayer structure as Graphene/SiC/InSb/SiC/Al was performed at 2−15 THz frequency region. The whole structure was under an external static magnetic field, which was normal to the surface of the layers. The magnetic field was applied to induce the magneto-optical characteristics of the graphene and InSb layers. The Al layer at the end of the structure was utilized to improve the reflectance coefficient of the structure. The reflectance and Kerr rotation spectra of the structure were calculated using 4 by 4 transfer matrix method, and the effects of the strength of external magnetic field (B), environment temperature (T), and chemical potential of graphene (μc) were investigated on the mentioned spectra. The results showed that resonance behaviors were created in both of the spectra at the few particular frequencies. The most strong resonance was seen near the frequency υ=3.1 THz, and the reflectance coefficient and Kerr rotation angle at this frequency were affected by changing the B, T, and μc. It was revealed that one can obtain a particular reflectance coefficient and Kerr rotation angle at this resonance frequency by simultaneous adjustment of B, T, and μc.

基于V形孔阵结构薄膜的光学与磁光特性研究

基于V形孔阵结构薄膜的光学与磁光特性研究

Magneto and magneto-optical characteristics of semiconductor nano material with nonsymmetrical geometry

Magneto and magneto-optical characteristics of semiconductor nano material with nonsymmetrical geometry

Irradiation effect on the magneto-optical properties of Bi-doped silica optical fiber based on valence state change

Magneto-optical properties of Bi-doped silica optical fibers (BDF) and single mode fiber (SMF) before and after irradiation (0-3.0 kGy) are investigated. BDF is prepared by the atomic layer deposition (ALD) technique combined with the conventional modified chemical vapor deposition (MCVD) process. Before irradiation, the Verdet constant of BDF (1.64 rad/(Tm)) is 27.13% larger than that of SMF (1.29 rad/(Tm)) at 980 nm. Because the Verdet constants of both of them are positive values, this implies diamagnetic behaviors of fiber sample materials. After irradiation, the Verdet constant of SMF keeps increasing with the increase of radiation doses (0-3kGy). However, in the same radiation dose range, the Verdet constant of BDF is decreased first and then increased. It is decreased with the increase of gamma irradiation in the low-dose range (<0.3 kGy). Especially, the Verdet constant of BDF in 0.3 kGy is of a negative value and the Faraday rotation of it is anti-clockwise, which means the fiber sample exhibits paramagnetic material properties. When the radiation dose is from 0.3 to 3 kGy, the Verdet constants of the BDF is increased. Furthermore, in a 3 kGy treatment, the Verdet constant of BDF (1.87 rad/(Tm)) is 23.84% larger than that of SMF (1.51 rad/Tm), and is 44.96% larger than that of SMF without irradiation treatment. The novel change of magneto-optical characteristics of the BDF sample may mainly result from irradiation-induced valence state change of bismuth ions.