ORCID Profile
0000-0003-4618-2535
Current Organisation
KU Leuven
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Publisher: AIP Publishing
Date: 05-2012
DOI: 10.1063/1.4712033
Abstract: A numerical implementation of the transition state theory is presented which can be used to calculate the attempt frequency f0 of arbitrary shaped magnetic nanostructures. The micromagnetic equations are discretized using the finite element method. The climbing image nudged elastic band method is used to calculate the saddle point configuration, which is required for the calculation of f0. Excellent agreement of the implemented numerical model and analytical solutions is obtained for single domain particles. The developed method is applied to compare f0 for single phase and graded media grains of advanced recording media. f0 is predicted to be comparable if the maximum anisotropy is the same in these two media types.
Publisher: AIP Publishing
Date: 06-07-2009
DOI: 10.1063/1.3170234
Abstract: We study vortex spin torque oscillators based on magnetic point contacts that operate in zero applied magnetic field. Static and dynamic vortex modes are shown to exist and have distinct electrical signatures. For the oscillatory mode, a spectrally pure slightly asymmetric voltage waveform is observed. It is subject to phase noise as sole fluctuations. The waveforms observed indicate that the vortex orbits outside the point contact region, with a pinned layer magnetization that is static but spatially nonuniform as a result of the current. This nonuniformity results in a reduction in the dc to rf power transduction yield.
Publisher: IOP Publishing
Date: 09-2009
Publisher: American Physical Society (APS)
Date: 23-06-2008
Publisher: American Physical Society (APS)
Date: 28-02-2003
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 11-2012
Publisher: Elsevier
Date: 2005
Publisher: AIP Publishing
Date: 15-07-2010
DOI: 10.1063/1.3456497
Abstract: We present a numerical study of oscillation modes in magnetic tunnel junction nanopillars and investigate the frequency and the full width at half maximum of the power spectrum as a function of applied field and applied current. We show that the line width reaches a minimum of 14.5 MHz as the system approaches the threshold current, and increases sharply to 308 MHz as the current is increased beyond the threshold current. The initial line narrowing is due to an increased coherence in the uniform precession mode, while the line broadening above threshold arises from the intrinsic oscillator nonlinearity combined with overlapping contributions from edge modes. We show that these results are in good agreement with recent experiments on MgO-based oscillators.
Publisher: Wageningen Academic Publishers
Date: 12-08-2022
Publisher: IOP Publishing
Date: 25-11-2009
Publisher: Wageningen Academic Publishers
Date: 26-08-2019
Publisher: Springer Science and Business Media LLC
Date: 04-2005
Publisher: Wageningen Academic Publishers
Date: 21-06-2021
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 09-2002
Publisher: AIP Publishing
Date: 09-11-2009
DOI: 10.1063/1.3263727
Abstract: We study the agility of current-tunable oscillators based on a magnetic vortex orbiting around a point contact in spin valves. The theory predicts that frequency tuning by currents occurs at constant orbital radius so an exceptional agility is anticipated. To test this, we have inserted an oscillator in a microwave interferometer to apply abrupt current variations while time resolving its emission. Using frequency shift keying, we show that the oscillator can switch between two stabilized frequencies differing by 25% in less than ten periods. With a wide frequency tunability and a good agility, such oscillators possess desirable figures of merit for modulation-based rf applications.
Publisher: SPIE
Date: 20-08-2009
DOI: 10.1117/12.826879
No related grants have been discovered for Lore D'Anvers.