Room temperature spin injection study across semi-crystalline PVDF-HFP thin films in PVDF-HFP/NiFe bilayers and Ag/(NiFe or Co)/PVDF-HFP/NiFe spin valves.

Spin injection across 160 nm thick semi-crystalline Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) is methodically investigated at room temperature in PVDF-HFP/NiFe bilayers and Ag/(NiFe or Co)/PVDF-HFP/NiFe vertical organic spin valves (OSVs) using both the co-planar waveguide ferromagnetic resonance (CPW-FMR: 7-35 GHz) and magnetoresistance (MR) techniques. The structural and microstructural characteristics of PVDF-HFP reveal the formation of mixed non-ferroelectric alpha and ferroelectric beta phases. The spin injection due to the transfer of angular momentum in PVDF-HFP/NiFe is quantified by measuring the spin-mixing conductance () and the enhancement in Gilbert damping () parameters from CPW-FMR data.

Temperature selectivity for single phase hydrothermal synthesis of PEG-400 coated magnetite nanoparticles.

Herein, we have presented a detailed investigation of the temperature effect on hydrothermal synthesis of FeO magnetic nanoparticles (MNPs). The appearance of single-phase cubic spinel FeO at and above critical temperature provides a clear indication that temperature plays a crucial role in the single-phase synthesis of the FeO MNPs. A detailed investigation of the structural, magnetic and spin dynamic properties of PEG-400 coated FeO MNPs synthesized by a facile hydrothermal method at different temperatures (120 °C, 140 °C, 160 °C and 180 °C for 16 hours) has been presented.

Microwave spin resonance investigation on the effect of the post-processing annealing of CoFeO nanoparticles.

A novel investigation on the finite-size effects on the spin resonance properties of cobalt ferrite (CoFeO) nanoparticles has been performed using a room temperature ferromagnetic resonance (FMR) technique. A single broad spectrum was obtained for the CoFeO nanoparticle samples, which indicated that all the samples were showing ferromagnetic characteristics. An asymmetric FMR line shape with a hefty trailing section was obtained due to the high magneto-crystalline anisotropy in CoFeO nanoparticles, which changed with the size distribution.

Dipolar Interaction and Magneto-Viscoelasticity in Nanomagnetic Fluid.

We investigate the effect of dilution on dipolar interaction with linear and non-linear rheological properties of kerosene based magnetic fluid. The steady-state behavior demonstrate a shear thinning behavior and corroborated with a power law, (η = c n + η∞) exponent, n ≤ 1. The shear-induced-breakup (separation) of nanoparticles and the yielding behavior has been explained by Bingham model.

Trapping and injecting single domain walls in magnetic wire by local fields.

A single domain wall (DW) moves at linearly increasing velocity under an increasing homogeneous drive magnetic field. Present experiments show that the DW is braked and finally trapped at a given position when an additional antiparallel local magnetic field is applied. That position and its velocity are further controlled by suitable tuning of the local field.

Finite-size scaling in band ferromagnets with non-universal critical behavior.

The ultra-high sensitivity of the ferromagnetic resonance (FMR) technique has been fully exploited to study the finite-size effects in the critical region near the ferromagnetic to paramagnetic phase transition in Cr(75-x)Fe(25+x) (x = 0, 5) thin films of high structural and magnetic quality. Conclusive experimental evidence is provided for the validity of finite-size scaling. Irrespective of the film thickness and composition, the critical exponents β, γ and ν for spontaneous magnetization, initial magnetic susceptibility and spin-spin correlation length retain their bulk values so that no dimensionality crossover occurs within the film thickness range covered in the FMR experiments.

Structural and Mössbauer effect investigations of amorphous FeCuNbSiB alloys nanocrystallized (VITROPERM) in magnetic field.

Melt-spun amorphous ribbons of nominal composition Fe73Cu1Nb3Si16B7, annealed at 560-580 degrees C for 1 hour in a magnetic field (H) applied along the width in the ribbon plane, develop uniaxial magnetic anisotropy with easy axis along H and exhibit several novel attributes. The samples labelled as S20 and S150 are nanocomposites consisting of ferromagnetic nanocrystalline grains (volume fraction approximately equal to 84% and 81%) of mean size d = 13(2) nm embedded in a ferromagnetic amorphous matrix and possess a magnetic permeability as large as 20,000 and 150,000, respectively. While nearly 55% of the nanocrystalline grains have a cubic DO3 Fe3Si-like structure with actual Si concentration of about 22 at.