Elaboration of Single Crystalline AU/NI80FE20/CU/NI80FE20/NIO(111) Spin Valves

2000 ◽  
Vol 619 ◽  
Author(s):  
C. Mocuta ◽  
A. Barbier ◽  
S. Lafaye ◽  
P. Bayle-Guillemaud
Keyword(s):  
Magnetic Properties ◽  
Giant Magnetoresistance ◽  
Magnetic Layer ◽  
Growth Conditions ◽  
Spin Valves ◽  
High Coercivity ◽  
Magnetic Exchange ◽  
Transmission Electron ◽  
Magnetic Exchange Coupling

ABSTRACTThe successful preparation of fully epitaxial spin-valves elaborated on NiO(111) single crystals is reported. The growth conditions of a smooth 2D permalloy (Py = Ni80Fe20) layer have been determined. A very strong magnetic exchange interaction is evidenced on the Py/NiO(111) interface. It strongly modifies the magnetic properties of Py that acquires high coercivity, leaving it as a hard magnetic material. The second Py layer has unchanged magnetic properties and plays the role of the sensing soft magnetic layer. A giant magnetoresistance (GMR) of 3.5% at room temperature was easily obtained without optimizing the thickness of the different layers. Complementarily energy-filtered (EF-) and high-resolution (HR-) transmission electron microscopy (TEM) were used to fully characterize the spin valves. Within the framework of magnetic exchange coupling, our results open the possibility to elaborate model spin valves in which the role of each interface can be investigated and controlled at the atomic level. The detrimental effect of an inter-diffusion at the Py/NiO interface is evidenced.

Role of the Epitaxy Relations in the CoCrPt Thin Films with Bilayer V/Cr Underlayers

1994 ◽  
Vol 343 ◽  
Author(s):  
Pawel Glijer ◽  
John M Sivertsen ◽  
Jack H Judy
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Structural Parameters ◽  
Magnetic Layer ◽  
Magnetic Film ◽  
The Other ◽  
High Coercivity ◽  
State Of Stress ◽  
Similar Texture

ABSTRACTThe effects of grain-to-grain epitaxy conditions on the magnetic properties of high coercivity CoCr13Pt13 films with bilayer Cr/Cr, V/Cr and V/V underlayers were studied. V/Cr films were used in order to obtain underlayers that would differ from Cr only by a size of the lattice constant. Introduction of V instead of Cr as an underlayer changed the relative misfits between CoCrPt and the underlayer lattice and increased the amount of {0002} texture in the magnetic film. This effect led to a decrease in the in-plane coercivity. CoCrPt/V/Cr and CoCrPt/Cr/Cr films exhibited similar texture of the underlayer, the same microstructure and similar level of internal stress. Correspondingly the decrease in coercivity did not exceed 10% (from 2.7 kOe to 2.5 kOe). On the other hand CoCrPt/V/V film had more than 4 times smaller coercivity (0.6 kOe). In this case, change in the magnetic properties was caused not only by altered misfits but also by the change in microstructure, texture and state of stress in the film. Results obtained indicate that small changes in misfits between a magnetic layer and an underlayer can be effectively used to control coercivity only if other structural parameters remain unchanged.

scholarly journals Phasin PhaP1 is involved in polyhydroxybutyrate granules morphology and in controlling early biopolymer accumulation in Azospirillum brasilense Sp7

AMB Express ◽  
2019 ◽  
Vol 9 (1) ◽  
Author(s):  
María de los Angeles Martínez-Martínez ◽  
Bertha González-Pedrajo ◽  
Georges Dreyfus ◽  
Lucía Soto-Urzúa ◽  
Luis Javier Martínez-Morales
Keyword(s):  
Azospirillum Brasilense ◽  
C:N Ratio ◽  
Growth Conditions ◽  
Low Oxygen ◽  
Rt Pcr ◽  
Transmission Electron ◽  
Azospirillum Brasilense Sp7 ◽  
Plant Growth Promoting ◽  
Growth Promoting

Abstract Phasins are amphiphilic proteins involved in the regulation of the number and size of polyhydroxybutyrate (PHB) granules. The plant growth promoting bacterium Azospirillum brasilense Sp7 accumulates high quantities of bioplastic PHB as carbon and energy source. By analyzing the genome, we identified six genes that code for proteins with a Phasin_2 domain. To understand the role of A. brasilense Sp7 PhaP1 (PhaP1Abs) on PHB synthesis, the phaP1 gene (AMK58_RS17065) was deleted. The morphology of the PHB granules was analyzed by transmission electron microscopy (TEM) and the PHB produced was quantified under three different C:N ratios in cultures subjected to null or low-oxygen transfer. The results showed that PhaP1Abs is involved in PHB granules morphology and in controlling early biopolymer accumulation. Using RT-PCR it was found that phasin genes, except phaP4, are transcribed in accordance with the C:N ratio used for the growth of A. brasilense. phaP1, phaP2 and phaP3 genes were able to respond to the growth conditions tested. This study reports the first analysis of a phasin protein in A. brasilense Sp7.

scholarly journals Thickness dependence and the role of spin transfer torque in nonlinear giant magnetoresistance of permalloy dual spin valves

2010 ◽  
Vol 82 (22) ◽  
Author(s):  
N. Banerjee ◽  
A. Aziz ◽  
M. Ali ◽  
J. W. A. Robinson ◽  
B. J. Hickey ◽  
...  
Keyword(s):  
Giant Magnetoresistance ◽  
Spin Transfer Torque ◽  
Thickness Dependence ◽  
Spin Transfer ◽  
Spin Valves

Role of growth conditions on magnetic properties of AlCrN grown by molecular beam epitaxy

2005 ◽  
Vol 86 (5) ◽  
pp. 052101 ◽  
Author(s):  
R. M. Frazier ◽  
G. T. Thaler ◽  
J. Y. Leifer ◽  
J. K. Hite ◽  
B. P. Gila ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Growth Conditions

DEPENDENCE OF GIANT MAGNETORESISTANCE ON THE THICKNESS OF MAGNETIC AND NON-MAGNETIC LAYERS IN DUAL SPIN VALVES

2004 ◽  
Vol 18 (09) ◽  
pp. 355-365 ◽  
Author(s):  
YONG WANG ◽  
MING XU ◽  
ZHENHONG MAI
Keyword(s):  
Giant Magnetoresistance ◽  
Classical Model ◽  
Spin Valve ◽  
Magnetic Layer ◽  
Spin Valves ◽  
Experimental Result ◽  
Magnetic Layers ◽  
Ferromagnetic Layers ◽  
Hole Effect ◽  
Good Agreement

Based on the previous semi-classical model, we have performed calculation of the giant magnetoresistance (GMR) as a function of the thickness of the top/bottom or center ferromagnetic layers and the non-magnetic layer in dual spin valves. Our results are in good agreement with that reported in experiment, i.e., a GMR maximum is observed when the thickness of the top/bottom magnetic layer is at 20 ~ 40 Å; the GMR value decreases monotonically with the increase of the non-magnetic layer thickness. By considering the "pin-hole" effect, the variation of GMR versus the thickness of the center magnetic layer is also found to be consistent with the experimental result. These calculations will be helpful in the design of high-quality spin-valve structures.

Magnetic Hardening of Mechanically Alloyed Pr2Co7

2012 ◽  
Vol 1471 ◽  
Author(s):  
L. Bessais ◽  
R. Fersi ◽  
M. Cabié ◽  
N. Mliki
Keyword(s):  
Magnetic Properties ◽  
Mechanical Milling ◽  
Annealing Temperature ◽  
High Vacuum ◽  
Anisotropy Field ◽  
Milling Process ◽  
Subsequent Annealing ◽  
High Coercivity ◽  
Mechanically Alloyed ◽  
Transmission Electron

ABSTRACTThe Pr2Co7 alloys are known to crystallize in two polymorphic forms: a hexagonal of the Ce2Ni7 type structure and a rhombohedral of the Gd2Co7 one. They were synthesized by mechanical milling and subsequent annealing in high vacuum. In this work, we focus on the structural study of these phases using X-ray diffraction and transmission electron microscopy. Also, we present the evolution of magnetic properties of these compounds vs the annealing temperature. The coercivity increases with annealing temperature reaching a maximum for TA = 800 °C. The highest is equal to 18 kOe at 293 K and 23 kOe at 10 K. The high magnetic properties observed in these nanostructured Pr2Co7 intermetallic alloys have their origin in its relatively high uniaxial magnetocrystalline anisotropy field, and in the homogeneous nanostructure developed by mechanical milling process and subsequent annealing. This high coercivity is attributed to the high anisotropy field of the Pr2Co7 phase and its nanoscale grain size. This leads to the formation of a magnetically hard Pr2Co7 phase.

Sign in / Sign up

Export Citation Format

Share Document