1,721,323 research outputs found
Micromagnetic computation of interface conductance of spin-transfer driven ferromagnetic resonance in nanopillar spin valves
No full textMicromagnetic computations are used to describe spin-transfer driven ferromagnetic resonance in nanopillar spin valves with elliptical cross section. Analytical uniform magnetization models reproduce the resonance phenomenon adequately and these can be used to compute interface conductance. In this work, using the magnetic parameters extracted by fitting static magnetoresistance measurements, mixing conductances are obtained; these values are 25% and 20% lower than the ones previously reported. Nonuniform magnetization resonance is foun
Core losses computation in micro-motors by using DME solver and micromagnetic simulations
No full textMicromagnetic simulations of linewidths and nonlinear frequency shift coefficient in spin torque nano-oscillators
No full textThe dependence of the linewidth on the temperature and the applied magnetic field angle is studied in spin torque nano-oscillators (STNOs) by means of full micromagnetic simulations. The analyzed spin valve is the experimental one by Sankey [Phys. Rev. Lett. 96, 227601 (2006)] and the magnetic parameters are given by magnetoresistance fitting. Linewidth behavior increases with the temperature, in agreement with the analytical predictions by Tiberkevich [Phys. Rev. B 78, 092401 (2008)], and its slope depends on the applied field angle. Also, the nonlinear frequency shift coefficient, which gives a measure of the nonlinearity degree of STNO and indicates the strength of the transformation of amplitude into phase fluctuations, is found. The understanding of the nonlinear frequency shift allows one to tune the generation frequency of the STNO, but, at the same time, creates an additional source of the phase noise, which leads to a significant broadening of the linewidth generation. Narrow linewidths (around 10 MHz at 0 K and 100 MHz at 300 K) are found in our shape-anisotropy nanopillars by applying close to in-plane magnetic field at an angle of 45° between in-plane easy and hard axes
Core losses computation in micro-motors by using DME solver and micromagnetic simulations
No full textMicromagnetic simulations of magnetization reversal by spin-polarized current in nanopillars with perpendicular anisotropy
No full textSpin-torque oscillators using perpendicular anisotropy in CoFeB–MgO magnetic tunnel junctions
No full textA new class of magnetic tunnel junctions (MTJ) with perpendicular anisotropy has been recently used for fast switching applications. A theoretical investigation for these materials to be applied as microwave nano-oscillators is here reported. We demonstrate micro-magnetically the possibility to have both high frequency and high power microwave emission at zero field in a double magnetic tunnel junction. Our predictions give rise to the design of a more compact and easily embedded spin-torque oscillators for all-on-chip applications. To increase the oscillator power, we also demonstrate the possibility to obtain frequency locking at zero field by applying a low current at microwaves
Spin-torque nanoscillator linewidths driven by spin-polarized currents: temperature and applied field angle dependence
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