scholarly journals Limits for the vortex state spin torque oscillator in magnetic nanopillars: Micromagnetic simulations for a thin free layer

2010 ◽  
Vol 108 (12) ◽  
pp. 123914 ◽  
Author(s):  
Gloria R. Aranda ◽  
Julian M. Gonzalez ◽  
Juan J. del Val ◽  
Konstantin Y. Guslienko
Keyword(s):  
Vortex State ◽  
Spin Torque ◽  
Free Layer ◽  
Micromagnetic Simulations ◽  
Magnetic Nanopillars ◽  
State Spin

Modeling of the perpendicular polarizer-planar free layer spin torque oscillator: Micromagnetic simulations

2008 ◽  
Vol 78 (2) ◽  
Author(s):  
I. Firastrau ◽  
D. Gusakova ◽  
D. Houssameddine ◽  
U. Ebels ◽  
M.-C. Cyrille ◽  
...  
Keyword(s):  
Spin Torque ◽  
Free Layer ◽  
Micromagnetic Simulations

scholarly journals Electrical characterisation of higher order spin wave modes in vortex-based magnetic tunnel junctions

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Alex. S. Jenkins ◽  
Lara San Emeterio Alvarez ◽  
Samh Memshawy ◽  
Paolo Bortolotti ◽  
Vincent Cros ◽  
...  
Keyword(s):  
Spin Wave ◽  
Tunnel Junctions ◽  
Magnetic Tunnel Junctions ◽  
Higher Order ◽  
Spin Torque ◽  
Micromagnetic Simulations ◽  
Higher Order Modes ◽  
Spin Diode ◽  
Super High Frequency ◽  
Wave Modes

AbstractNiFe-based vortex spin-torque nano-oscillators (STNO) have been shown to be rich dynamic systems which can operate as efficient frequency generators and detectors, but with a limitation in frequency determined by the gyrotropic frequency, typically sub-GHz. In this report, we present a detailed analysis of the nature of the higher order spin wave modes which exist in the Super High Frequency range (3–30 GHz). This is achieved via micromagnetic simulations and electrical characterisation in magnetic tunnel junctions, both directly via the spin-diode effect and indirectly via the measurement of the coupling with the gyrotropic critical current. The excitation mechanism and spatial profile of the modes are shown to have a complex dependence on the vortex core position. Additionally, the inter-mode coupling between the fundamental gyrotropic mode and the higher order modes is shown to reduce or enhance the effective damping depending upon the sense of propagation of the confined spin wave.

scholarly journals Magnetization Dynamics in a Perpendicular Anisotropy Free Layer under a Spin Torque Effect with Crossed Polarization

2020 ◽  
Vol 25 (1) ◽  
pp. 54
Author(s):  
Nafeesa Rahman ◽  
Rachid Sbiaa
Keyword(s):  
Tunnel Junction ◽  
Magnetic Tunnel Junction ◽  
Film Plane ◽  
Spin Torque ◽  
Spin Angular Momentum ◽  
Perpendicular Anisotropy ◽  
Free Layer ◽  
Magnetization Dynamics ◽  
Magnetization Direction ◽  
Spin Polarized

The transfer of spin angular momentum from a spin polarized current provides an efficient way of reversing the magnetization direction of the free layer of the magnetic tunnel junction (MTJ), and while faster reversal will reduce the switching energy, this in turn will lead to low power consumption. In this work, we propose a design where a spin torque oscillator (STO) is integrated with a conventional magnetic tunnel junction (MTJ) which will assist in the ultrafast reversal of the magnetization of the free layer of the MTJ. The structure formed (MTJ stacked with STO), will have the free layer of the MTJ sandwiched between two spin polarizer layers, one with a fixed magnetization direction perpendicular to film plane (main static polarizer) and the other with an oscillatory magnetization (dynamic polarizer). The static polarizer is the fixed layer of the MTJ itself and the dynamic polarizer is the free layer of the STO.

scholarly journals Nanoscale true random bit generator based on magnetic state transitions in magnetic tunnel junctions

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Alex S. Jenkins ◽  
Lara San Emeterio Alvarez ◽  
Paulo P. Freitas ◽  
Ricardo Ferreira
Keyword(s):  
Tunnel Junctions ◽  
Magnetic State ◽  
Magnetic Tunnel Junctions ◽  
Vortex State ◽  
Magnetic Vortex ◽  
State Transitions ◽  
Free Layer ◽  
Plane Field ◽  
Random Bit Generator ◽  
Ac Current

Abstract We present an investigation into the in-plane field induced free layer state transitions found in magnetic tunnel junctions. By applying an ac current into an integrated field antenna, the magnetisation of the free layer can be switched between the magnetic vortex state and the quasi-uniform anti-parallel state. When in the magnetic vortex state, the vortex core gyrates a discrete number of times, and at certain frequencies there is a 50% chance of the core gyrating n or n − 1 times, leading to the proposal of a novel nanoscale continuous digital true random bit generator.

scholarly journals Noise Characterization of Vortex-State GMR Sensors with Different Free Layer Thicknesses

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 1013
Author(s):  
Herbert Weitensfelder ◽  
Hubert Brueckl ◽  
Armin Satz ◽  
Dieter Suess
Keyword(s):  
Spin Valve ◽  
Low Frequency ◽  
Vortex State ◽  
Frequency Noise ◽  
Free Layer ◽  
Low Frequencies ◽  
Gmr Sensors ◽  
Noise Characterization ◽  
Higher Sensitivity

The spin valve principle is the most prominent sensor design among giant- (GMR) and tunneling (TMR) magnetoresistive sensors. A new sensor concept with a disk shaped free layer enables the formation of a flux-closed vortex magnetization state if a certain relation of thickness to diameter is given. The low frequency noise of current-in-plane GMR sensing elements with different free layer thicknesses at different external field strengths has been measured. The measurements of the 1/f noise in external fields enabled a separation of magnetic and electric noise contributions. It has been shown that while the sensitivity is increasing with a decreasing element thickness, the pink noise contribution is increasing too. Still the detection limit at low frequencies is better in thinner free layer elements due to the higher sensitivity.

Observations of thermally excited ferromagnetic resonance on spin torque oscillators having a perpendicularly magnetized free layer

2014 ◽  
Vol 115 (17) ◽  
pp. 17C740 ◽  
Author(s):  
S. Tamaru ◽  
H. Kubota ◽  
K. Yakushiji ◽  
M. Konoto ◽  
T. Nozaki ◽  
...  
Keyword(s):  
Ferromagnetic Resonance ◽  
Spin Torque ◽  
Free Layer ◽  
Spin Torque Oscillators

scholarly journals Magnetization dynamics in spin torque nano-oscillators: Vortex state versus uniform state

2009 ◽  
Vol 80 (5) ◽  
Author(s):  
R. Lehndorff ◽  
D. E. Bürgler ◽  
S. Gliga ◽  
R. Hertel ◽  
P. Grünberg ◽  
...  
Keyword(s):  
Vortex State ◽  
Spin Torque ◽  
Magnetization Dynamics ◽  
Uniform State

Enhanced power of spin torque oscillators with Permalloy free layer

2017 ◽  
Author(s):  
C. Murapaka ◽  
E. Jimenez ◽  
K. Merazzo-Jaimes ◽  
A. Ruiz-Calaforra ◽  
R. Ferreira ◽  
...  
Keyword(s):  
Spin Torque ◽  
Free Layer ◽  
Spin Torque Oscillators
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