Giant Magnetoresistance Research Papers - Academia.edu (original) (raw)

We report ballistic magnetoresistance (BMR) values in magnetic nanocontacts for Ni, Co, and Fe. The samples range from atomic nanocontacts (smaller than 1nm cross-section) to stable electrodeposited nanocontacts (up to 30nm cross-section). The experiments are done at room temperature and up to 4kOe applied field. We obtain values of stable BMR up to 700%. By manipulating the resistance and the

- by David Pommerenke
- •
- Power Systems, Giant Magnetoresistance, Printed Circuit Board, Circuit Switching
- by Laszlo Peter and +1
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- Engineering, Giant Magnetoresistance, Compositional Analysis, Physical sciences
- by Qinfang Zhang
- •
- Giant Magnetoresistance, Physical sciences, Magnetic Properties, CHEMICAL SCIENCES

Giant magnetoresistance (GMR) in spin valves is due to spin-dependent scattering occurring at ferromagnet/normal metal (F/N) interfaces and/or in the ferromagnetic layers. In a spin valve with a typical F/N/F structure where the spin scattering asymmetry factor (alpha) of both F/N interfaces is the same (more or less than 1), the GMR is expected to be positive. If alpha is greater than one at one F/N interface and less than one at the other F/N interface, however, the GMR is expected to be negative. Here, we show that the F1/Cu/SAF/Cu/F2/IrMn dual spin valve structure exhibits negative GMR, where F1 and F2 are CoFe and SAF = CoFe/Ru t/CoFe, due to both opposite electron spin scattering asymmetry factor at the CoFe/Ru/CoFe interfaces as well as the electrical separation of the overall structure into two GMR spin valves connected in parallel. A GMR of 6% is observed in the structure without the Ru spacer layer, insertion of a 0.6 nm thick Ru in the SAF results in a negative GMR ratio of -3% , which becomes positive again at the Ru thickness of 0.8 nm, the oscillation from positive to negative MR is consistent with interlayer exchange coupling period across the Ru spacer.

- by Ciaran Fowley
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- Giant Magnetoresistance, Spin Valve Structures, Dual Spin Valves
- by Neil Goldfine
- •
- Giant Magnetoresistance, Aerospace, Sensor Arrays, IEEE

Anisotropic Magnetoresistors (AMRs) and recently also Giant Magnetoresistors (GMRs) are the latest competitors of small-size fluxgate sensors. AMR bridges using barber-pole geometry are linear devices; their performance can be improved by... more

- by Sergio Arana
- •
- Analytical Chemistry, Biomedical Engineering, Biosensors, Flow Cytometry
- by P. Holody and +1
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- Mechanical Engineering, Condensed Matter Physics, Giant Magnetoresistance, Magnetization Reversal
- by Laszlo Peter
- •
- Engineering, Microstructure, Giant Magnetoresistance, Magnetic field
- by Larissa Panina
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- Materials Engineering, Mechanical Engineering, Giant Magnetoresistance, Thin Film
- by Xavier Batlle
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- Engineering, Giant Magnetoresistance, Physical sciences, Spin Wave

Solid state physics made a considerable progress towards nanometer- and subnanometer-size structures during the last decade. The structures encompass ultra thin films, multilayers, tubes, pillars, particles, clusters, etc. In this work, we address some of them. In particular, multilayers and spin valves with nm and sub-nm thickness of individual layers and ordered monolayers of nanoparticles are discussed in detail. These

- by Matej Jergel
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- Giant Magnetoresistance, Self Assembly, X Rays, Thin Film
- by A. Nogaret
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- Materials Engineering, Condensed Matter Physics, Spintronics, Giant Magnetoresistance
- by Brad Miller
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- Engineering, Magnetic Recording, Giant Magnetoresistance, Physical sciences
- by Artur Lopes Ribeiro and +1
- •
- Signal Processing, Giant Magnetoresistance, Non Destructive Testing, Nondestructive testing
- by Helena Ramos
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- Giant Magnetoresistance, Magnetic field, Sensors, IEEE
- by Mohindar Seehra
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- Giant Magnetoresistance, Thin Film, Superlattices

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 for the read sensor applications. The exchange biased SV with Co2 Fe(Al0.5 Si0.5) alloy showed a resistance change-area product (ΔRA) of 6 m Ωμm2 and an MR ratio of 21% at room temperature when the Co2 Fe(Al0.5 Si0.5) layer was well-B2-ordered by a high temperature annealing at 500°C. The critical bias current density for the spin torque effect on the reduction of ΔRA was ~ 3 × 107 A/cm2. Based on the high spin polarization directly measured by the point contact Andreev reflection method, Co2 (Cr0.1 Fe0.9 )Si, Co2 Mn(Ga0.5 Sn0.5 ), and Co2 Fe(Ge0.5 Ga0.5) alloy thin films were investigated for CPP-GMR SVs. Among them, the Co2Fe(Ge0.5Ga0.5) alloy showed a high CPP-GMR ratio in the pseudo SVs exceeding 40% at RT and 120% at 10 K.

- by Hari Srinivas Goripati
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- Spintronics, Giant Magnetoresistance, Heusler Alloys, Read Head Sensor

Rotating magnetic field eddy-current (RoFEC) probe for nondestructive evaluation of steam generator tubes in a nuclear power plant offers an alternate method that has compact configuration and higher speed compared to traditional bobbin coil, rotating probe coils, and array probes. This paper investigates the feasibility of the proposed RoFEC eddy-current probe which is composed of three windings excited by three-phase ac current and does not require mechanical rotation of probe. Results of finite-element modeling using reduced magnetic vector potential (RMVP) formulation are presented for modeling the inspection of ferromagnetic and nonferromagnetic tubes. Design parameters of the excitation coils and GMR pick-up sensor are optimized by means of a parametric study.

- by Junjun Xin
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- Engineering, Giant Magnetoresistance, Nondestructive Evaluation, Sensor Arrays
- by Hari Srinivas Goripati
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- Spintronics, Giant Magnetoresistance, Heusler Alloys, CPP-GMR
- by Hari Srinivas Goripati
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- Spintronics, Giant Magnetoresistance, Heusler Alloys, Spin Transfer Torque
- by Artur Lopes Ribeiro and +1
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- Signal Processing, Giant Magnetoresistance, Measurement systems, Sensors
- by Hichem Eleuch
- •
- Giant Magnetoresistance
- by Stuart Parkin
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- Giant Magnetoresistance, Magnetic field, Room Temperature
- by Manh-huong Phan
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- Engineering, Giant Magnetoresistance, Magnetic Materials, Physical sciences

Double perovskite Y2FeCrO6nanoparticles of diameter 40–60 nm have been prepared by a
molten salt synthesis procedure. These exhibit ferromagnetic and relaxor-type ferroelectric
transition. The presence of both Fe
2+
and Cr
2+
species is confirmed by XPS analysis. The
magnetic properties have been explained on the basis of superexchange interaction between
Fe
2+
/Fe
3+
and Cr
2+
/Cr
3+
and also Kanamori–Goodenough coupling between Fe
3+
/Cr
3+
species. The relaxor-type behaviour is ascribed to dielectric loss arising due to small polaron
hopping conduction between Fe
2+
/Fe
3+
and Cr
2+
/Cr
3+
pairs, respectively. A large
magnetodielectric coefficient (∼25%) at room temperature is caused by a∼30% negative
magnetoresistance for a magnetic field of 1.7 T. This has been explained by a model in which
spin-polarized electrons hopping through the antiphase boundary contribute higher electrical
conductivity to the system when a magnetic field is applied to it.

- by Ramaprasad Maiti
- •
- Giant Magnetoresistance
- by Krzysztof Warda
- •
- Quantum Physics, Giant Magnetoresistance, Transport Properties, Spectrum
- by Laszlo Peter and +1
- •
- Materials Engineering, Mechanical Engineering, Giant Magnetoresistance, Small Angle X Ray Scattering
- by Himadri Majumdar
- •
- Giant Magnetoresistance, Transport Properties, New, Physical sciences
- by Stuart Wolf
- •
- Giant Magnetoresistance, Magnetic field, Physical sciences, Magnetic Properties

We present small angle scattering measurements performed on Fe–Ag granular systems using polarised neutrons. Various samples with different iron concentration have been investigated and the analysis of the experimental data points out that samples morphology does not change remarkably with Fe content. Finally, the study of the polarised signal indicates the presence of Fe rich regions in the nanometer range of size having a negligible magnetisation.

The structure of metallic multilayer systems has been established to be important and of big interest both in basic research as well as in technological processes. The aim of this work is to study the formation, the structure and the evolution of near surface layers and of buried inter- faces, mainly by means of new perturbed gamma-gamma angular correlation spectrometer. The measurements are based on in-situ film preparation in an UHV-system in the Institute of Nuclear Physics, Cracow. The development and putting into operation of the thin film evaporation system was performed. Also the testing of the measurement setup and the data acquisition system for the γ-γ-perturbed angular spectrometer (PAC) was continued. A series of metallic multilayer systems were produced and studied by X-ray diffraction (XRD) and X-ray reflection (XRR) (Münster, MS), scanning force microscopy (SFM) (1,2) and giant magnetoresistivity (GMR) (Kraków, KR), which was recently added to the tools for thin layer...

- by Jacek Jaworski
- •
- Materials Science, Giant Magnetoresistance, Thin Film, Data acquisition
- by Sayani Majumdar
- •
- Giant Magnetoresistance, Transport Properties, New, Physical sciences

Eddy-current inspection for nondestructive evaluation has traditionally been investigated in terms of coil impedance signals via theoretical and experimental methods. However, advanced eddy-current techniques use solid-state sensors such as Hall devices, giant magnetoresistive sensors, anisotropic magnetoresistive sensors, and superconducting quantum interference devices for magnetic field measurement to achieve better sensitivity and high temporal and spatial resolution in material evaluation and

- by kamar el aidoudi
- •
- Giant Magnetoresistance
- by Juan Jose Palacios
- •
- Physics, Materials Science, Surfaces and Interfaces, Giant Magnetoresistance