Function Of Magnetic Configuration Research Articles

Ultrafast laser-induced magneto-optical response of CoFeB/MgO/CoFeB magnetic tunneling junction

Understanding of ultrafast spin dynamics is crucial for future ultrafast and energy efficient magnetic memory and storage applications. We study the ultrafast laser-induced magneto-optical response of a CoFeB/MgO/CoFeB magnetic tunneling junction (MTJ), when exciting with a short laser pulse, as a function of magnetic configuration and pump fluence. The ultrafast magnetization of the MTJ drops rapidly in the timescale of 0.33–0.37 ps, which is driven by both electron-spin scattering and spin transport mutually. Subsequently, the energy from the electron and spin reservoirs transfers into the lattice with the timescale of 1.5–2.0 and 5.0–15.0 ps through the electron–phonon and spin–phonon interactions, respectively. Our results suggest that the interfacial spin-orientation of CoFeB/MgO/CoFeB could modulate the interaction constant between spins and phonons. These findings provide insight into the role of MTJ interface in spin dynamics, which will be helpful for opto-spintronic tunnel junction stack designs and applications.

Current-induced dynamics in noncollinear dual spin valves

Spin-transfer torque and current induced spin dynamics in spin-valve nanopillars with the free magnetic layer located between two magnetic films of fixed magnetic moments is considered theoretically. The spin-transfer torque in the limit of diffusive spin transport is calculated as a function of magnetic configuration. It is shown that non-collinear magnetic configuration of the outermost magnetic layers has a strong influence on the spin torque and spin dynamics of the central free layer. Employing macrospin simulations we make some predictions on the free layer spin dynamics in spin valves composed of various magnetic layers. We also present a formula for critical current in non-collinear magnetic configurations, which shows that the magnitude of critical current can be several times smaller than that in typical single spin valves.

A comparison of H-mode pedestal characteristics in MAST as a function of magnetic configuration and ELM type

The H-mode pedestal characteristics on MAST are measured in a variety of connected double null (CDN) and single null divertor (SND) discharges. In CDN discharges the edge density pedestal width in spatial co-ordinates is similar on both the high and the low field sides suggesting that the width may be determined by neutral penetration. However, in SND discharges the density pedestal width appears to be a flux surface quantity, which suggests that the scrape-off-layer may have a role to play in determining the density pedestal width. In both CDN and SND discharges the temperature pedestal width appears to be a flux surface quantity. The pedestal characteristics and edge stability have been studied as a function of the ELM type. The edge temperature pedestal is found to have a weak dependence on , but increases with βpol as .

Superthermal electrons in the TJ-IU torsatron

The generation and behaviour of superthermal electrons are studied as a function of magnetic configuration in the TJ-IU torsatron. Characterization of fast electrons is carried out with soft x-ray (SXR) and hard x-ray (HXR) diagnostic systems, covering the range from 0.4 keV to several MeV. The mean energies reached by the superthermal electron populations are found to be consistent with the occurrence of electron cyclotron (EC) off-axis absorption for the different radial magnetic field ripples at the axis. The interpretation of the experimental observations has been based on the influence of trapping factors at the magnetic axis and electron density profiles in the superthermal electron mean energy and density.