Spin-Transfer-Torque Driven Vortex Dynamics in Electrodeposited Nanowire Spin-Valves

SPIN ◽  
2017 ◽  
Vol 07 (01) ◽  
pp. 1740007 ◽  
Author(s):  
Flavio Abreu Araujo ◽  
Luc Piraux
Keyword(s):  
Magnetic Field ◽  
Porous Alumina ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Microwave Emission ◽  
Spin Valves ◽  
Zero Magnetic Field ◽  
Micromagnetic Simulations ◽  
Magnetic Layers ◽  
In Series

A bottom-up approach for the fabrication of an assembly of electrodeposited nanowires has been combined to single nanowire electrical connection techniques to investigate the spin-transfer-torque and microwave emission of specially designed nanowires containing Co/Cu/Co pseudo spin-valves (SVs). Porous alumina templates are used for the growth by electrodeposition of metallic in-series connected SVs. Under specific magnetic field and injected current conditions, emission of microwave current is detected with frequency in the GHz range and linewidth as low as 1.8[Formula: see text]MHz. Microwave signals have been obtained even at zero magnetic field and high frequency versus magnetic field tunability was demonstrated. Our findings are in good agreement with micromagnetic simulations. In addition, it appears that in our particular geometry, the microwave emission is generated by the vortex gyrotropic motion which occurs in, at least, one of the two magnetic layers of our SV structures.

Thermal spin-transfer torque driven by the spin-dependent Seebeck effect in metallic spin-valves

2015 ◽  
Vol 11 (7) ◽  
pp. 576-581 ◽  
Author(s):  
Gyung-Min Choi ◽  
Chul-Hyun Moon ◽  
Byoung-Chul Min ◽  
Kyung-Jin Lee ◽  
David G. Cahill
Keyword(s):  
Spin Transfer Torque ◽  
Seebeck Effect ◽  
Spin Transfer ◽  
Spin Valves

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 Shaped angular dependence of the spin-transfer torque and microwave generation without magnetic field

2007 ◽  
Vol 3 (7) ◽  
pp. 492-497 ◽  
Author(s):  
O. Boulle ◽  
V. Cros ◽  
J. Grollier ◽  
L. G. Pereira ◽  
C. Deranlot ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Angular Dependence ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Microwave Generation

Resonant excitation of coupled skyrmions by spin-transfer torque

2016 ◽  
Vol 30 (02) ◽  
pp. 1550254 ◽  
Author(s):  
Y. Y. Dai ◽  
H. Wang ◽  
T. Yang ◽  
Z. D. Zhang
Keyword(s):  
Microwave Field ◽  
Amplitude Ratio ◽  
Alternating Current ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Resonant Excitation ◽  
Dual Frequency ◽  
Magnetostatic Interaction ◽  
Micromagnetic Simulations

Resonant excitations of coupled skyrmions in Co/Ru/Co nanodisks activated by spin-transfer torque (STT) have been studied by micromagnetic simulations. It is found that STT is an effective method to manipulate skyrmion dynamics. Unlike the dynamics driven by a microwave field, two skyrmions with opposite chiralities move synchronously in the same direction when they are driven by STT, which makes it easier to observe the dynamics of coupled skyrmions in experiments. Resonant excitations of coupled skyrmions can be controlled by changing the frequency or amplitude ratio of a dual-frequency alternating current (AC). In addition, the magnetostatic interaction between the two skyrmions plays an important role in the dynamics of coupled skyrmions.

scholarly journals Theoretical Study of Field-Free Switching in PMA-MTJ Using Combined Injection of STT and SOT Currents

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1345
Author(s):  
Shaik Wasef ◽  
Hossein Fariborzi
Keyword(s):  
Critical Current ◽  
Theoretical Study ◽  
Tunnel Junctions ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Spin Orbit ◽  
Micromagnetic Simulations ◽  
Spintronic Devices ◽  
Current Densities ◽  
The Relationship

Field-free switching in perpendicular magnetic tunnel junctions (P-MTJs) can be achieved by combined injection of spin-transfer torque (STT) and spin-orbit torque (SOT) currents. In this paper, we derived the relationship between the STT and SOT critical current densities under combined injection. We included the damping–like torque (DLT) and field-like torque (FLT) components of both the STT and SOT. The results were derived when the ratio of the FLT to the DLT component of the SOT was positive. We observed that the relationship between the critical SOT and STT current densities depended on the damping constant and the magnitude of the FLT component of the STT and the SOT current. We also noted that, unlike the FLT component of SOT, the magnitude and sign of the FLT component of STT did not have a significant effect on the STT and SOT current densities required for switching. The derived results agreed well with micromagnetic simulations. The results of this work can serve as a guideline to model and develop spintronic devices using a combined injection of STT and SOT currents.

All Perpendicular Spin Nano-Oscillators with Composite Free Layer

SPIN ◽  
2019 ◽  
Vol 09 (03) ◽  
pp. 1940010
Author(s):  
Jiaqi Wei ◽  
Kaihua Cao ◽  
Hushan Cui ◽  
Kewen Shi ◽  
Wenlong Cai ◽  
...  
Keyword(s):  
Low Cost ◽  
Single Layer ◽  
Perpendicular Magnetic Anisotropy ◽  
Magnetic Tunnel Junction ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Microwave Emission ◽  
Emission Frequency ◽  
Large Current ◽  
High Emission

Owing to improved thermal stability and scalability, materials with perpendicular magnetic anisotropy (PMA) are extremely attractive. The all perpendicular magnetic tunnel junction ([Formula: see text]-MTJ) devices are primarily devoted to spin transfer torque (STT)-induced switching and few works report their microwave emission. Here, we demonstrate the basic results of RF function in nanoscale [Formula: see text]-MTJ which has two different thickness free layers separated by atom-thick tungsten insertion. The ultrathin W spacer layer not only enables the two CoFeB free layers precess as a single layer but also greatly enhances the PMA which further induces high-emission frequency. The all perpendicular spin transfer torque nano-oscillator (STNO) exhibited high frequency (7.6[Formula: see text]GHz) and large current modulation capability of [Formula: see text] at moderate external magnetic field. Along with our previous work on STT switching utilizing the similar stack, such a multifunctional structure could bring low cost solutions to Internet of Things (IoT) network applications.

Tuning Resonance Frequency of Spin Wave Localized in an Isolated Skyrmion by Magnetoelectric Couplings

SPIN ◽  
2019 ◽  
Vol 09 (03) ◽  
pp. 1950009 ◽  
Author(s):  
Rongzhi Zhao ◽  
Wenchao Chen ◽  
Chenglong Hu ◽  
Luyang Chen ◽  
Jian Zhang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Resonant Frequency ◽  
Total Energy ◽  
Average Energy ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Integer Multiple ◽  
External Perturbations ◽  
Out Of Plane ◽  
Oscillation Frequencies

Understanding the dynamic behavior of an isolated skyrmion with external perturbations has been obstructed due to the difficulty in experimentally observing such an instantaneous phenomenon within picoseconds. Herein, we theoretically investigated the spin-transfer-torque-induced dynamics of an isolated skyrmion excited by external nanosecond-pulse perturbations. It is found that a redshift of the resonant frequency appears under a pulse polarized current with [Formula: see text][Formula: see text]A/m2 and [Formula: see text][Formula: see text]GHz, while a blueshift is presented under a combined perturbation of the pulse polarized current and an out-of-plane ac magnetic field. The physic origins of the redshift and the blueshift are ascribed to the increased average energy of system from [Formula: see text][Formula: see text]J to [Formula: see text][Formula: see text]J and integer multiple (twofold and fourfold) oscillation frequencies of total energy, respectively. The present study could thus provide an insight to the micromagnetic dynamics of skyrmion under the magnetoelectric couplings.

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