Magnetoresistance in a deformed Cu-Ni-Fe alloy with ultrafine multilayer structure

1994 ◽  
Vol 9 (5) ◽  
pp. 1134-1139 ◽  
Author(s):  
L.H. Chen ◽  
S. Jin ◽  
T.H. Tiefel ◽  
R. Ramesh
Keyword(s):  
Temperature Dependence ◽  
Multilayer Structure ◽  
Giant Magnetoresistance ◽  
Room Temperature ◽  
Phase Interface ◽  
Ferromagnetic Phase ◽  
Dramatic Improvement ◽  
Two Phase ◽  
Magnetoresistance Ratio ◽  
Spin Dependent Scattering

The creation of a giant magnetoresistance (GMR) effect in a spinodally decomposed and deformed Cu-20% Ni-20% Fe alloy is reported. The alloy is processed to contain a locally multilayered superlattice-like structure with alternating ferromagnetic and nonmagnetic layers with a size scale of 10-20 Å. The microstructural modification produced a dramatic improvement in room-temperature magnetoresistance ratio from ∼0.6 to ∼5%. The observed magnetoresistance is most likely related to the spin-dependent scattering at the two-phase interface and in the ferromagnetic phase, although the exact mechanism involved may be qualitatively different from the usual GMR picture. A rather unusual temperature-dependence of magnetoresistance ratio, i.e., the room-temperature value being greater than that at 4.2 K, was found.

Large Magnetoresistance Variation of Pseudo Spin Valves with Different Nano Oxide Layer Position

2007 ◽  
Vol 1032 ◽  
Author(s):  
Jeong Dae Suh ◽  
C.A. Ross
Keyword(s):  
Surface Roughness ◽  
Oxide Layer ◽  
Multilayer Structure ◽  
Giant Magnetoresistance ◽  
Spin Valves ◽  
Resistance Change ◽  
Nano Oxide ◽  
Shunting Effect ◽  
Spin Dependent Scattering ◽  
Layer Position

AbstractWe have investigated the influence of the nano-oxide layer positions on giant magnetoresistance(GMR) of the NiFe(9nm)/Cu(4nm)/Co(5nm) pseudo spin valves. Nano-oxide layer positions had a several effects on the multilayer structure that changes its magnetotransport behavior. GMR ratio varied between 2.8% and 0.15% depending on the nano-oxide layer positions within the stack. The increase of the GMR ratio was accompanied by increase in resistance change, decrease in sheet resistance, and decrease in surface roughness. These significant variations of GMR ratio was explained by the changes on the spin dependent scattering or current shunting effect. Our results showed that appropriate placement of a nano-oxide layer was essential fo optimize magnetoresistance and properties of spin valves.

Giant magnetoresistance at room temperature achieved in the ferromagnetic phase of powder La0.5Sr0.5MnO3

1998 ◽  
Vol 66 (1-4) ◽  
pp. 99-107 ◽  
Author(s):  
E. Dhahri ◽  
K. Guidara ◽  
A. Cheikhrouhou ◽  
J. C. Joubert ◽  
J. Pierre
Keyword(s):  
Giant Magnetoresistance ◽  
Room Temperature ◽  
Ferromagnetic Phase

Giant Magnetoresistance in FeMn/NiCoFe/Cu/NiCoFe Spin Valve Prepared by Opposed Target Magnetron Sputtering

2014 ◽  
Vol 979 ◽  
pp. 85-89 ◽  
Author(s):  
Ramli ◽  
Euis Sustini ◽  
Nurlaela Rauf ◽  
Mitra Djamal
Keyword(s):  
Magnetron Sputtering ◽  
Layer Thickness ◽  
Coercive Field ◽  
Giant Magnetoresistance ◽  
Room Temperature ◽  
Spin Valve ◽  
Ferromagnetic Layer ◽  
Vibrating Sample Magnetometer ◽  
Magnetoresistance Ratio ◽  
Scanning Electron

The giant magnetoresistance (GMR) effect in FeMn/NiCoFe/Cu/NiCoFe spin valve prepared by dc opposed target magnetron sputtering is reported. The spin valve thin films are characterized by Scanning Electron Microscopy (SEM), Vibrating Sample Magnetometer (VSM) and magnetoresistance ratio measurements. All measurements are performed in room temperature. The inserted 45 mm thickness FeMn layer to the NiCoFe/Cu/NiCoFe system can increase the GMR ratio up to 32.5%. The coercive field to be increased is compared with different FeMn layer thickness. Furthermore, the coercive field (Hc) decreases with increasing FeMn layer thickness. Magnitude of coercive field is 0.1 T, 0.09 T and 0.08 T for FeMn layer thickness is 30 nm, 45 nm and 60 nm, respectively. The FeMn layer is used to lock the magnetization in the ferromagnetic layer through the exchange anisotropy. This paper will describe the development of a GMR spin valve and its magnetic properties.

Microstructures and Mechanical Properties of Two-Phase FeNiMnAl Alloys

2014 ◽  
Vol 783-786 ◽  
pp. 2549-2554 ◽  
Author(s):  
Ian Baker ◽  
Xiao Lan Wu ◽  
Fan Ling Meng ◽  
Paul R. Munroe
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Temperature Dependence ◽  
Room Temperature ◽  
High Strength ◽  
Two Phase ◽  
Nanostructured Alloys ◽  
Microstructures And Mechanical Properties ◽  
Very High

This paper presents an overview of the microstructures found in a range of two-phase FeNiMnAl alloys ranging from near-equiatomic very high-strength nanostructured alloys, such Fe30Ni20Mn25Al25, to more ductile f.c.c./B2 alloys, such as Fe30Ni20Mn35Al15. The effect of annealing at 823 K on the room temperature hardness is presented together with the temperature dependence of the yield strength.

scholarly journals Perpendicular giant magnetoresistance of Co/Cu multilayers on grooved substrates: Systematic analysis of the temperature dependence of spin-dependent scattering

1996 ◽  
Vol 53 (21) ◽  
pp. 14024-14027 ◽  
Author(s):  
W. Oepts ◽  
M. A. M. Gijs ◽  
A. Reinders ◽  
R. M. Jungblut ◽  
R. M. J. van Gansewinkel ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Giant Magnetoresistance ◽  
Systematic Analysis ◽  
Spin Dependent Scattering

Thermal Characterization of Cu∕CoFe Multilayer for Giant Magnetoresistive Head Applications

2005 ◽  
Vol 128 (2) ◽  
pp. 113-120 ◽  
Author(s):  
Y. Yang ◽  
R. M. White ◽  
M. Asheghi
Keyword(s):  
Electrical Resistance ◽  
Multilayer Structure ◽  
Giant Magnetoresistance ◽  
Room Temperature ◽  
Thermal Characterization ◽  
Disk Drive ◽  
Multilayer Structures ◽  
Large Decrease ◽  
Resistance Thermometry

Giant magnetoresistance (GMR) head technology is one of the latest advancements in the hard disk drive (HDD) storage industry. The GMR head multilayer structure consists of alternating layers of extremely thin metallic ferromagnetic and nonmagnetic films. A large decrease in the electrical resistivity from antiparallel to parallel alignment of the film magnetizations is observed, known as the GMR effect. The present work characterizes the in-plane electrical and thermal conductivities of Cu∕CoFe GMR multilayer structures in the temperature range of 50K to 340K using Joule-heating and electrical resistance thermometry on suspended bridges. The thermal conductivity of the GMR layer monotonically increases from 25Wm−1K−1 (at 55K) to nearly 50Wm−1K−1 (at room temperature). We also report a GMR ratio of 17% and a large magnetothermal resistance effect (GMTR) of 25% in the Cu∕CoFe multilayer structure.

Temperature Dependence of the Magnetoresistance of Co/Re Superlattices

2001 ◽  
Vol 674 ◽  
Author(s):  
Timothy Charlton ◽  
David Lederman ◽  
Gian P. Felcher
Keyword(s):  
Temperature Dependence ◽  
Giant Magnetoresistance ◽  
Easy Axis ◽  
Superconducting Magnet ◽  
Film Plane ◽  
Temperature Dependent ◽  
Ferromagnetic Layers ◽  
Magnetic Easy Axis ◽  
Spin Dependent Scattering ◽  
The Magnetic Field

ABSTRACTHcp (10.0) Co/Re superlattices were grown by dc magnetron sputtering on sapphire (11.0) substrates with the [00.1] direction of the superlattice in the film plane. The temperature-dependent magnetoresistance (MR) was measured on samples patterned by photolithography from 10 K to 300 K in a 5.5 T superconducting magnet. The pattern allows the measurement of the MR with the current (I) and the magnetic field (H) parallel or perpendicular to the magnetic easy axis (c, the [00.1] direction). Measurements at 5 K on an antiferromagnetically-coupled sample shows dips in the MR near H = 0 when H ∕∕ c and H ⊥ I, dips below the saturation value at H ∼ 2.5 kOe for H ∕∕ c and H ∕∕ I configuration due to the competition between the anisotropic magnetoresistance (AMR) and the giant magnetoresistance (GMR). Since the AMR is dependent on the transport within the ferromagnetic layers, the temperature dependence yields information about the relative magnitudes of interface vs. bulk spin-dependent scattering. Our analysis shows that the GMR is anisotropic and that the spin-dependent scattering occurs predominantly at the interfaces only for certain configurations.

Temperature dependence of the spin-dependent scattering in Co/Cu multilayers determined from perpendicular-giant-magnetoresistance experiments

1994 ◽  
Vol 50 (22) ◽  
pp. 16733-16736 ◽  
Author(s):  
M. A. M. Gijs ◽  
S. K. J. Lenczowski ◽  
R. J. M. van de Veerdonk ◽  
J. B. Giesbers ◽  
M. T. Johnson ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Giant Magnetoresistance ◽  
Spin Dependent Scattering

Giant Magnetoresistance Studies of NiFe-Based Spin-Valve Multilayers

1994 ◽  
Vol 343 ◽  
Author(s):  
Chien-Li Lin ◽  
John M. Sivertsen ◽  
Jack H. Judy
Keyword(s):  
Magnetic Field ◽  
Thermal Stability ◽  
Magnetic Properties ◽  
Multilayer Structure ◽  
Giant Magnetoresistance ◽  
Room Temperature ◽  
Spin Valve ◽  
Vibrating Sample Magnetometer ◽  
Recording Head ◽  
Annealing Experiments

ABSTRACTThe giant magnetoresistance in FeMn exchange-biased NiFe-based multilayer spin-valve structures prepared by rf-diode sputtering technique were studied. Experiments were performed on samples with different thicknesses of each layer in these multilayers. The magnetic properties were measured using a vibrating sample magnetometer and the giant magnetoresistance was measured using an in-line four-point magnetoresistance probe. A magnetoresistance of 6.5% in a magnetic field of less than 15 Oe was obtained in a Cu(30Å)/FeMn(150Å)/NiFe(50Å)/Co(15Å)/ Cu(20Å)/Co(15Å)/NiFe(60Å) multilayer structure at room temperature. Annealing experiments of these multilayers were performed to study the thermal stability during the recording head fabrication processes. No degradation in the magnetoresistance has been found for annealing these films at 230°C up to four hours.

Magnetic Properties of Hitperm (Fe,Co)88Zr7B4Cu1 Nanocrystalline Magnets (Invited)

1999 ◽  
Vol 577 ◽  
Author(s):  
M. A. Willard ◽  
M. Gingras ◽  
M. J. Lee ◽  
V. G. Harris ◽  
D. E. Laughlin ◽  
...  
Keyword(s):  
Room Temperature ◽  
Structural Phase ◽  
Core Loss ◽  
Nanocrystalline Alloy ◽  
Ferromagnetic Phase ◽  
Phase Transformation Temperature ◽  
Scanning Calorimetry ◽  
Two Phase ◽  
Differential Scanning Calorimetry Study ◽  
X Ray

ABSTRACTAlloys consisting of Fe-Co-M-B-Cu (with M = Zr, Hf, Nb), called HITPERM alloys, have been developed. Synchrotron X-radiation studies have been used to show that the ferromagnetic phase in an equiatomic FeCo-based alloy is the α'-FeCo phase. Since both the α'-FeCo phase and the FeCo-based amorphous phase of the nanocrystalline alloy have high Curie temperatures, a high magnetization persists up to the α -> γ structural phase transformation temperature of 980°C. Room temperature AC permeability measurements have shown that the alloys maintain a high permeability of ∼2000 up to a frequency of 20 kHz. The room temperature core loss has also been shown to be competitive with commercial high temperature magnetic alloys with a value of 1 W/g at Bs = 10 kG andf= 10 kHz. Analysis of extended X-ray absorption fine structure (EXAFS) data is consistent with a two-phase mixture of nanocrystalline body centered cubic derivative FeCo structure and an amorphous Zr-rich phase. A differential scanning calorimetry study of the primary crystallization reaction shows an activation energy of 323.3 kJ/mol. As a preliminary study of phase and grain stability, broadening of X-ray diffraction peaks indicates little grain growth after annealing at 600 °C for 3072 hours.

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