scholarly journals Heterostructures for Realizing Magnon-Induced Spin Transfer Torque

2012 ◽  
Vol 2012 ◽  
pp. 1-7
Author(s):  
P. B. Jayathilaka ◽  
M. C. Monti ◽  
J. T. Markert ◽  
Casey W. Miller
Keyword(s):  
Giant Magnetoresistance ◽  
Spin Valve ◽  
Building Blocks ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Buffer Layers ◽  
High Quality ◽  
Spacer Layer Thickness ◽  
Spacer Layer ◽  
Structural And Magnetic Properties

This work reports efforts fabricating heterostructures of different materials relevant for the realization of magnon-induced spin transfer torques. We find the growth of high-quality magnetite on MgO substrates to be straightforward, while using transition metal buffer layers of Fe, Cr, Mo, and Nb can alter the structural and magnetic properties of the magnetite. Additionally, we successfully fabricated and characterized Py/Cr/Fe3O4and Fe3O4/Cr/Fe3O4spin valve structures. For both, we observe a relatively small giant magnetoresistance and confirm an inverse dependence on spacer layer thickness. Thus, we have shown certain materials combinations that may form the heterostructures that are the building blocks necessary to achieve magnon-induced spin transfer torque devices.

Introduction of spin torques

2017 ◽  
Author(s):  
T. Kimura
Keyword(s):  
Angular Momentum ◽  
Giant Magnetoresistance ◽  
Spontaneous Magnetization ◽  
Magnetic Domain ◽  
Magnetic Multilayers ◽  
Transfer Effect ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Spin Angular Momentum ◽  
Spin Torques

This chapter discusses the spin-transfer effect, which is described as the transfer of the spin angular momentum between the conduction electrons and the magnetization of the ferromagnet that occurs due to the conservation of the spin angular momentum. L. Berger, who introduced the concept in 1984, considered the exchange interaction between the conduction electron and the localized magnetic moment, and predicted that a magnetic domain wall can be moved by flowing the spin current. The spin-transfer effect was brought into the limelight by the progress in microfabrication techniques and the discovery of the giant magnetoresistance effect in magnetic multilayers. Berger, at the same time, separately studied the spin-transfer torque in a system similar to Slonczewski’s magnetic multilayered system and predicted spontaneous magnetization precession.

Multiple Reflection Effect on Spin-Transfer Torque Dynamics in Spin Valves with a Single or Dual Polarizer

SPIN ◽  
2015 ◽  
Vol 05 (01) ◽  
pp. 1550003 ◽  
Author(s):  
Weiwei Zhu ◽  
Zongzhi Zhang ◽  
Jianwei Zhang ◽  
Yaowen Liu
Keyword(s):  
Spin Valve ◽  
Spin Transfer Torque ◽  
Multiple Reflection ◽  
Spin Transfer ◽  
Reflection Effect ◽  
Multiple Reflections ◽  
Applied Current ◽  
Negative Current ◽  
Ferromagnetic Layers ◽  
Scattering Matrix Method

In this paper, spin-dependent multiple reflection effect on spin-transfer torque (STT) has been theoretically and numerically studied in a spin valve nanopillar with a single or dual spin-polarizer. By using a scattering matrix method, we formulate an analytical expression of STT that contains the multiple interfacial reflection effect. It is found that the multiple reflections could enhance the STT efficiency and reduce the critical switching current. The STT efficiency depends on the spin polarization of both the free layer and polarizer. In the nanopillars with a dual spin polarizer, the multiple reflections would cause an asymmetric frequency dependence on the applied current, albeit exactly the same parameters are used in all three ferromagnetic layers, indicating that the frequency in the negative current varies much faster than that in the positive case.

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.

Field Dependence of Switching Currents in an Exchange Biased Spin Valve

2007 ◽  
Vol 7 (1) ◽  
pp. 344-349
Author(s):  
Hoang Yen Thi Nguyen ◽  
Sung-Jung Joo ◽  
Kuyoul Jung ◽  
Kyung-Ho Shin
Keyword(s):  
Magnetic Field ◽  
Field Dependence ◽  
Spin Valve ◽  
Spin Transfer Torque ◽  
Information Storage ◽  
Spin Transfer ◽  
Field Range ◽  
Higher Spin ◽  
Thermal Magnetization ◽  
Negative Field

Current induced magnetic reversal due to spin transfer torque is a promising candidate in advanced information storage technology. It has been intensively studied. This work reports the field-dependence of switching-currents for current induced magnetization switching in a uncoupled nano-sized cobalt-based spin valve of exchange biased type. The dependency is investigated in hysteretic regime at room temperature, in comparison with that of a trilayer simple spin valve. In the simple spin valve, the switching currents behave to the positive and the negative applied magnetic field symmetrically. In the exchange biased type, in contrast, the switching currents respond to the negative field in a quite unusual and different manner than to the positive field. A negative magnetic field then can shift the switching-currents into either negative or positive current range, dependently on whether a parallel or an antiparallel state of the spin valve was produced by that field. This different character of switching currents in the negative field range can be explained by the effect of the exchange bias pinning field on the spin-polarizer (the fixed Co layer) of the exchange biased spin valve. That unidirectional pinning filed could suppress the thermal magnetization fluctuation in the spin-polarizer, leading to a higher spin polarization of the current, and hence a lower switching current density than in the simple spin valve.

scholarly journals A New Circuit Model for Spin-Torque Oscillator Including Perpendicular Torque of Magnetic Tunnel Junction

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Hyein Lim ◽  
Sora Ahn ◽  
Miryeon Kim ◽  
Seungjun Lee ◽  
Hyungsoon Shin
Keyword(s):  
Tunnel Junction ◽  
Giant Magnetoresistance ◽  
New Technology ◽  
Magnetic Tunnel Junction ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Spin Torque ◽  
Mean Oscillation ◽  
Proposed Model ◽  
Level Model

Spin-torque oscillator (STO) is a promising new technology for the future RF oscillators, which is based on the spin-transfer torque (STT) effect in magnetic multilayered nanostructure. It is expected to provide a larger tunability, smaller size, lower power consumption, and higher level of integration than the semiconductor-based oscillators. In our previous work, a circuit-level model of the giant magnetoresistance (GMR) STO was proposed. In this paper, we present a physics-based circuit-level model of the magnetic tunnel junction (MTJ)-based STO. MTJ-STO model includes the effect of perpendicular torque that has been ignored in the GMR-STO model. The variations of three major characteristics, generation frequency, mean oscillation power, and generation linewidth of an MTJ-STO with respect to the amount of perpendicular torque, are investigated, and the results are applied to our model. The operation of the model was verified by HSPICE simulation, and the results show an excellent agreement with the experimental data. The results also prove that a full circuit-level simulation with MJT-STO devices can be made with our proposed model.

scholarly journals DATA STORAGE: REVIEW OF HEUSLER COMPOUNDS

SPIN ◽  
2012 ◽  
Vol 02 (04) ◽  
pp. 1230006 ◽  
Author(s):  
ZHAOQIANG BAI ◽  
LEI SHEN ◽  
GUCHANG HAN ◽  
YUAN PING FENG
Keyword(s):  
Data Storage ◽  
Giant Magnetoresistance ◽  
Functional Materials ◽  
Recent Decade ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Magnetic Data ◽  
Heusler Compounds ◽  
Storage Devices ◽  
The Family

In the recent decade, the family of Heusler compounds has attracted tremendous scientific and technological interest in the field of spintronics. This is essentially due to their exceptional magnetic properties, which qualify them as promising functional materials in various data-storage devices, such as giant-magnetoresistance spin valves, magnetic tunnel junctions, and spin-transfer torque devices. In this article, we provide a comprehensive review on the applications of the Heusler family in magnetic data storage. In addition to their important roles in the performance improvement of these devices, we also try to point out the challenges as well as possible solutions, of the current Heusler-based devices. We hope that this review would spark further investigation efforts into efficient incorporation of this eminent family of materials into data storage applications by fully arousing their intrinsic potential.

Efficient spin transfer torque in pseudo-spin-valve structure

2008 ◽  
Vol 103 (7) ◽  
pp. 07A718 ◽  
Author(s):  
J. Guo ◽  
M. B. A. Jalil ◽  
S. G. Tan
Keyword(s):  
Spin Valve ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Valve Structure
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