Spin polarization in magnets

2017 ◽  
Author(s):  
K. Takanashi ◽  
Y. Sakuraba
Keyword(s):  
Spin Polarization ◽  
Spin Current ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Energy Band Gap ◽  
Magnetoresistance Effect ◽  
Half Metals ◽  
Conduction Electrons ◽  
Spin Polarized ◽  
Spin Dependent Scattering

This chapter explains how the exchange splitting between up- and down-spin bands in ferromagnets unexceptionally generates spin-polarized electronic states at the Fermi energy. The quantity of spin polarization P in ferromagnets is one of the important parameters for application in spintronics, since a ferromagnet having a higher P is able to generate larger various spin-dependent effects such as the magnetoresistance effect, spin transfer torque, spin accumulation, and so on. However, the spin polarizations of general 3d transition metals or alloys generally limit the size of spin-dependent effects. Thus,“‘half-metals” attract much interest as an ideal source of spin current and spin-dependent scattering because they possess perfectly spin-polarized conduction electrons due to the energy band gap in either the up- or down-spin channel at the Fermi level.

Enhancing Frequency and Reducing the Power of Spin-Torque Nanooscillator By The Generated Oersted Field

SPIN ◽  
2020 ◽  
Vol 10 (02) ◽  
pp. 2050012
Author(s):  
H. Bhoomeeswaran ◽  
P. Sabareesan
Keyword(s):  
Spin Valve ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Spin Torque ◽  
Spintronic Devices ◽  
Frequency Tunability ◽  
Spin Polarized ◽  
The Individual ◽  
Promising Source ◽  
Nonmagnetic Spacer

The current-driven magnetization precession dynamics stimulated by Spin-Transfer Torque (STT) in a trilayer spin-valve device (typically Spin-Torque Nanooscillator (STNO)) is numerically investigated by solving the Landau–Lifshitz–Gilbert–Slonczewski (LLGS) equation. We have devised four STNO devices made of ferromagnetic alloys such as CoPt, CoFeB, Fe[Formula: see text]B[Formula: see text]Ni2 and EuO, which act as free and fixed layers. Here, copper acts as a nonmagnetic spacer for all the devices. In this work, we have introduced the current-induced Oersted field, which is generated when a spin-polarized current passes through the device. The generated Oersted field strength is varied by increasing the diameter of the STNO device. Frequency tunability is achieved in all the four devices, whereas the power of the individual device reduces. The frequency and power of the devices depend entirely on the saturation magnetization of the material, which inherently reflects in the current density and the coherence of the spin-polarized DC. In all devices, the frequency increases, whereas the power decreases by increasing the strength of the Oersted field. Among the four devices, the maximum frequency can be tuned up to 104[Formula: see text]GHz with 40[Formula: see text]nm device diameter, which is obtained for EuO material. This opens a promising source and paves a glittering future for the nanoscale spintronic devices.

A QUANTUM MODEL FOR THE GIANT MAGNETORESISTANCE EFFECT

1996 ◽  
Vol 10 (17) ◽  
pp. 2103-2110
Author(s):  
LEI ZHOU ◽  
RUIBAO TAO
Keyword(s):  
Simple Model ◽  
Electric Conductivity ◽  
Giant Magnetoresistance ◽  
Quantum Model ◽  
Magnetoresistance Effect ◽  
Conduction Electrons ◽  
Giant Magnetoresistance Effect ◽  
Model Hamiltonian ◽  
Spin Dependent Scattering ◽  
Scattering Potential

A quantum explanation based on the previous semi-classical theory has been presented for the giant magnetoresistance (GMR) effect in this letter. A simple model Hamiltonian has been proposed for the conduction electrons in the magnetic layered structures in which the interaction of the conduction electrons with the local spins and the spin-dependent scattering potential have been considered, then an analytical expression of the effective electric conductivity is derived after some simplifying procedures. The main feature of the GMR effect may be explained by this simple model qualitatively.

Domain-wall pinning, nonadiabatic spin-transfer torque, and spin-current polarization in permalloy wires doped with vanadium

2010 ◽  
Vol 81 (2) ◽  
Author(s):  
S. Lepadatu ◽  
J. S. Claydon ◽  
C. J. Kinane ◽  
T. R. Charlton ◽  
S. Langridge ◽  
...  
Keyword(s):  
Domain Wall ◽  
Spin Current ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Domain Wall Pinning

COMPARISON OF THE SPIN POLARIZATION OF THE PHOTOELECTRON DIFFRACTION SPECTRA FOR DIFFERENT STRUCTURE MODELS OF MAGNETITE (111) LAYERS

1997 ◽  
Vol 04 (05) ◽  
pp. 907-910 ◽  
Author(s):  
P. RENNERT ◽  
A. CHASSÉ ◽  
W. MÜCK
Keyword(s):  
Iron Oxide ◽  
Magnetic Structure ◽  
Spin Polarization ◽  
Phase Shifts ◽  
Magnetic Scattering ◽  
Photoelectron Diffraction ◽  
Spin Polarized ◽  
Scattering Phase ◽  
Spin Dependent Scattering ◽  
Scattering Phase Shifts

Layers of magnetite structure were observed in deposing iron oxide on Pd by LEED measurements. We consider the magnetic structure of these layers. It is investigated whether spin-polarized and angle-resolved photoelectron diffraction can be used to dstinguish between the Zuo and the Mizoguchi model, respectively. In the two models we have a different distribution of the Fe 2+ and Fe 3+ ions. This difference is incorporated into the calculation by spin-dependent scattering phase shifts. The results of the calculation show that there is a cancellation of the magnetic scattering in the Mizoguchi structure whereas there remains a contribution in the Zuo model. Thus, we conclude that these structures should be distinguishable by spin-polarized angle-resolved photoelectron diffraction.

Evidence for Spin Polarization of Metallic Copper in CO/Cu and Fe/Cu Multilayers

1993 ◽  
Vol 313 ◽  
Author(s):  
S. Pizzini ◽  
C. Giorgetti ◽  
A. Fontaine ◽  
E. Dartyge ◽  
G. Krill ◽  
...  
Keyword(s):  
Spin Polarization ◽  
Metallic Copper ◽  
Magnetic Element ◽  
X Ray ◽  
Conduction Electrons ◽  
Magnetic Layers ◽  
Spin Polarized

ABSTRACTMagnetic circular x-ray dichroism measurements on CO/Cu and Fe/Cu Multilayers at the K edge of copper show that the 4p -states of copper are significantly spin-polarized by the adjacent magnetic layers. In relation to the phase opposition of the copper thickness-dependent magnetoresistance of CO/Cu and Fe/Cu Multilayers it is of prime importance to notice that the polarization of the conduction electrons of copper follows specifically the polarization of the conduction electrons of the adjacent magnetic element.

scholarly journals Spin‐Polarized Current, Spin‐Transfer Torque, and Spin Hall Effect in Presence of an Electromagnetic Non‐Minimal Coupling

2020 ◽  
Vol 532 (3) ◽  
pp. 1900357
Author(s):  
Rodrigo Turcati ◽  
Carlos Andres Bonilla Quintero ◽  
José Abdalla Helayël‐Neto ◽  
Enrique Arias
Keyword(s):  
Hall Effect ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Spin Hall Effect ◽  
Minimal Coupling ◽  
Spin Polarized

Experimental determination of spin-transfer torque nonadiabaticity parameter and spin polarization in permalloy

2009 ◽  
Vol 79 (9) ◽  
Author(s):  
S. Lepadatu ◽  
M. C. Hickey ◽  
A. Potenza ◽  
H. Marchetto ◽  
T. R. Charlton ◽  
...  
Keyword(s):  
Experimental Determination ◽  
Spin Polarization ◽  
Spin Transfer Torque ◽  
Spin Transfer
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