Nanocrystalline ${\mathrm{NiFe}}_{2}{\mathrm{O}}_{4}$ spinel has been synthesized with various grain sizes by high-energy ball milling. From the high-field magnetization studies and extended x-ray-absorption fine-structure, M\"ossbauer measurements in an external magnetic field of 5 T applied parallel to direction gamma rays, we could observe that ${\mathrm{Ni}}^{2+}$ ions occupy tetrahedral sites on grain-size reduction due The ${\mathrm{Fe}}^{3+}$ spins have a canted structure canting...

Fermi level tuning has been successfully demonstrated in Co-based full-Heusler alloy ${\mathrm{Co}}_{2}{\mathrm{FeAl}}_{0.5}{\mathrm{Si}}_{0.5}$ (CFAS). The half-metallic band gap of CFAS was proved by the behavior differential conductance $\mathrm{CFAS}/({\mathrm{MgAl}}_{2}){\mathrm{O}}_{x}/\mathrm{CoFe}$ magnetic tunneling junctions with an unexplored crystalline $({\mathrm{MgAl}}_{2}){\mathrm{O}}_{x}$ barrier. exhibits highest effective spin polarization (${P}_{\mathrm{eff}}$) at 300 K...

Equilibrium susceptibility ${\overline{\ensuremath{\chi}}}_{\mathrm{eq}}$ of frozen iron nitride magnetic fluids is estimated as the convergent value relaxation curves for various initial states. In lower temperature range in which field cooled ${\overline{\ensuremath{\chi}}}_{\mathrm{FC}}$ shows a plateau, dense sample nearly same ${\overline{\ensuremath{\chi}}}_{\mathrm{FC}}$, while diluted increases with decreasing temperature. These indicate that blocked moments are observed isolated...

A current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) spin valve using epitaxial layers of Co2FeAl0.5Si0.5 (CFAS) Heusler alloy as ferromagnetic electrodes is reported. multilayer stack Cr/Ag/CFAS/Ag/CFAS/Co75Fe25/Ir22Mn78/Ru was deposited on a MgO (001) single crystal substrate. Epitaxial growth the Cr, Ag, and CFAS in orientation up to top layer confirmed. Large MR ratios 6.9% at room temperature 14% 6 K were observed for CPP-GMR device. High polarization possible reason high ratios.

We report the transport properties of a current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) device with Co2Fe(Al0.5Si0.5) (CFAS) Heusler alloy ferromagnetic layers and Ag spacer layer. The CPP-GMR devices showed relatively high ΔRA values MR ratios up to 17 m Ω μm2 80% at 14 K, 8 34% 290 K. spin diffusion length ∼3 nm bulk asymmetry ∼0.77 for CFAS K were estimated by Valet–Fert model, indicating large contribution interfacial scattering.

Crystal structure and magnetic susceptibility were investigated for a thiospinel compound CuIr 2 S 4 , which exhibits transition from metallic to insulating on cooling at the temperature T c of 230 K. It was found that is accompanied by first-order structural transition. As cooled through transforms cubic tetragonal with volume contraction 0.7%. The phase has an axial ratio about 1.03. Magnetic susceptibility, paramagnetic in region, decreases sharply becomes diamagnetic cooling. mostly...

We fabricated fully epitaxial Fe/MgAl2O4/Fe(001) magnetic tunnel junctions using plasma oxidation of an Mg/Al bilayer. The MgAl2O4 showed a (001)-oriented spinel-type structure, and there were few misfit dislocations at the interfaces between two Fe layers due to small lattice mismatch (∼1%). Tunnel magnetoresistance (TMR) ratios up 117% (165%) obtained room temperature (15 K). bias voltage for one-half zero-bias TMR ratio (Vhalf) was relatively large, ranging from 1.0 1.3 V temperature,...

Using a newly developed highly spin-polarized Heusler alloy, Co2Fe(Ga0.5Ge0.5) (CFGG), as ferromagnetic layers, we have fabricated current-perpendicular-to-plane pseudospin valve with large resistance change-area product (ΔRA) of 9.5 mΩ μm2 and magnetoresistance (MR) ratio (100×ΔR/R) 41.7% at 300 K. These values were further enhanced to ΔRA=26.4 MR=129.1% 10 The MR are attributed the high spin polarization CFGG alloy confirmed by point contact Andreev reflection measurements.

We report large magnetoresistance (MR) output in fully epitaxial Co2Fe(Ge0.5Ga0.5)/Ag/Co2Fe(Ge0.5Ga0.5) current-perpendicular-to-plane pseudo spin valves. The resistance-area product change (ΔRA) of 12 mΩμm2 at room temperature (RT), equivalent to MR ratio 57%, and ΔRA = 33 10 K, 183%, were obtained by using L21-ordered Co2Fe(Ge0.5Ga0.5) ferromagnetic electrodes. bulk scattering asymmetry (β) estimated be ∼0.83 RT ∼0.93 K for the films Valet-Fert model, indicating that Co2FeGe0.5Ga0.5...

Anisotropic magnetoresistance (AMR) effect has been systematically investigated in various Heusler compounds Co2MnZ and Co2FeZ (Z = Al, Si, Ge, Ga) epitaxial films quantitatively summarized against the total valence electron number NV. It was found that sign of AMR ratio is negative when NV between 28.2 30.3, turns positive becomes below above indicating Fermi level (EF) overlaps with or conduction band edges half-metallic gap at ∼ respectively. We also find out magnitude gradually increases...

A 4-fold-symmetry hexagonal Ru emerging in epitaxial MgO/Ru/Co2FeAl/MgO heterostructures is reported, which an approximately Ru(023) growth attributes to the lattice matching between MgO, Ru, and Co2FeAl. Perpendicular magnetic anisotropy of Co2FeAl/MgO interface substantially enhanced. The tunnel junctions (MTJs) incorporating this structure give rise largest magnetoresistance for perpendicular MTJs using low damping Heusler alloys.

Co ferrites fabricated by a thermal oxidation have been tested as spin filter. Spin-filter efficiencies of 44% and 4.3% were confirmed at 10 K RT, respectively, using magnetic tunnel junction Pt/CoFe2O4/MgO/Co. By increasing the bias voltage, tunneling magnetoresistance (TMR) increases then decreases. This is interpreted via spin-down conduction band in ferrite. Since electron RT attributed to hopping on defect states ferrite, reduction defects will be key achieving higher spin-filter effect.

Solid solutions of BiGaxM1–xO3 (M = Cr, Mn, and Fe) were prepared using the high-pressure high-temperature method at 6 GPa 1700 K Cr 1300 Mn). The formation a large family polar materials with R3c Cm symmetries was found. Crystal structures studied laboratory X-ray powder diffraction: space group Cm, 5.3150(1) Å, b 5.2960(1) c 4.6965(1) β 92.556(2)° for BiGa0.4Fe0.6O3; 5.2798(1) 5.2577(1) 4.6465(1) 91.974(2)° BiGa0.7Mn0.3O3; R3c, 5.51623(8) Å 13.61391(17) BiGa0.4Cr0.6O3. Samples symmetry...

Effects of temperature changes on aging phenomena are studied for the spin-glass-like phase a ferromagnetic fine particle system. The results obtained during short experimental periods are, in appearance, asymmetric about changes. However, extension shows that effects symmetric. These can be explained by droplet model well.

The magnetic properties and the crystal structure of MgV2O4 Mg(V0.85Al0.15)2O4 have been studied. Both compounds are normal cubic spinels with highly frustrated lattice. Around T2=65 K, has orders accompanied cubic-tetragonal transition. Below T2, susceptibility shows complex behavior. In Mg(V0.85Al0.15)2O4, spin-glasslike state appears. V51-Knight shift an anomalous temperature dependence, which is not simply related by that susceptibility.

The temperature's rising: New multiferroic perovskites In1−xMxMO3 with x=0.112–0.176 and M=Fe0.5Mn0.5 (see picture) were prepared using high-pressure techniques. They have the same structure as BiFeO3 high Curie temperatures; in addition, they are canted antiferromagnets Néel temperatures close to room temperature.

We investigated the current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) of pseudo spin valves (PSVs) using ferromagnetic (FM) Heusler alloy Co2Fe(Ga1−xGex) (x = 0, 0.5, and 1) layers an Ag spacer layer. The FM layer with x 0.5 gave rise to highest MR output, ΔRA 8.7 mΩ·μm2, at room temperature 10 nm thick layers. output increased increasing annealing temperature, Ta, a maximum Ta 500 °C. Transmission electron microscopy showed no visible changes in layered structure; however,...

The thiospinel ${\mathrm{CuIr}}_{2}{\mathrm{S}}_{4}$ exhibits a temperature-induced metal-insulator $(M\ensuremath{-}I)$ transition around 226 K, showing hysteresis on heating and cooling, that manifests itself as gap in the electronic density of state with increasing electrical resistivity at low temperatures. Conversely, ${\mathrm{CuIr}}_{2}{\mathrm{Se}}_{4}$ remains metallic down to 0.5 K. We have successfully synthesized spinel-type compound...

Phase transitions of magnetic fluids in the zero field were studied from viewpoint static susceptibility and typical relaxation time order to distinguish between blocking phenomena. We used iron-nitride containing nearly uniform particles so as remove effects particle-size distribution. In densest sample, we observed growth ferromagnetic fluctuations and, diluted samples, a temperature-induced first-order phase transition.

We report the investigation of structure and magnetic properties full-Heusler alloy Co2FeAl0.5Si0.5 (CFAS) thin films grown on MgO-buffered MgO (001) substrates through magnetron sputtering. It was found that single-crystal CFAS with high degree L21 ordering sufficiently flat surface could be obtained after postdeposition annealing. All show a distinct uniaxial anisotropy easy axis magnetization along in-plane [110] direction. These results indicate use buffer for is promising approach...

We report magnetization switching by spin-transfer torque in an epitaxial spin-valve nanopillar made with a half-metallic full-Heusler Co2FeAl0.5Si0.5 (CFAS) alloy. The CFAS/Ag/CFAS spin valves showed magnetoresistance ratio of 7%–9%, and was clearly observed the applying relatively small dc current (∼106 A/cm2 density). Statistical analysis based on thermal activation model revealed averaged critical density (Jc0) 9.3×106 stability factor (KV/kBT) ∼40.

We studied various Heusler alloy compositions for the ferromagnetic layers of current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) spin-valves (SVs) to obtain large MR outputs read sensor applications. The exchange biased SV with Co <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Fe(Al xmlns:xlink="http://www.w3.org/1999/xlink">0.5</sub> Si ) showed a resistance change-area product (ΔRA) 6 m Ωμm <sup...