Proposal for piezoelectric-ferromagnet bilayer based microwave oscillators without any external magnetic field or spin transfer torque

2011 ◽  
Author(s):  
Debanjan Bhowmik ◽  
Sayeef Salahuddin
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Microwave Oscillators

Spin Transfer Torque in a Graphene Lateral Spin Valve Assisted by an External Magnetic Field

Nano Letters ◽  
2013 ◽  
Vol 13 (11) ◽  
pp. 5177-5181 ◽  
Author(s):  
Chia-Ching Lin ◽  
Ashish Verma Penumatcha ◽  
Yunfei Gao ◽  
Vinh Quang Diep ◽  
Joerg Appenzeller ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Spin Valve ◽  
Spin Transfer Torque ◽  
Spin Transfer

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

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.

Coupling of spin-transfer torque to microwave magnetic field: A micromagnetic modal analysis

2007 ◽  
Vol 101 (5) ◽  
pp. 053914 ◽  
Author(s):  
L. Torres ◽  
L. Lopez-Diaz ◽  
E. Martinez ◽  
G. Finocchio ◽  
M. Carpentieri ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Modal Analysis ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Microwave Magnetic Field

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.

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