18 research outputs found
Ferromagnetic resonance study of polycrystalline Fe_{1-x}V_x alloy thin films
Ferromagnetic resonance has been used to study the magnetic properties and
magnetization dynamics of polycrystalline FeV alloy films with
. Films were produced by co-sputtering from separate Fe and V
targets, leading to a composition gradient across a Si substrate. FMR studies
were conducted at room temperature with a broadband coplanar waveguide at
frequencies up to 50 GHz using the flip-chip method. The effective
demagnetization field and the Gilbert damping
parameter have been determined as a function of V concentration. The
results are compared to those of epitaxial FeV films
Spin-torque driven ferromagnetic resonance of Co/Ni synthetic layers in spin valves
Spin-torque driven ferromagnetic resonance (ST-FMR) is used to study thin
Co/Ni synthetic layers with perpendicular anisotropy confined in spin-valve
based nanojunctions. Field swept ST-FMR measurements were conducted with a
magnetic field applied perpendicular to the layer surface. The resonance lines
were measured under low amplitude rf excitation, from 1 to 20 GHz. These
results are compared with those obtained using conventional rf field driven FMR
on extended films with the same Co/Ni layer structure. The layers confined in
spin valves have a lower resonance field, a narrower resonance linewidth and
approximately the same linewidth vs frequency slope, implying the same damping
parameter. The critical current for magnetic excitations is determined from
measurements of the resonance linewidth vs dc current and is in accord with the
one determined from I-V measurements.Comment: 3 pages, 3 figure
Giant magnetoresistance by exchange springs in DyFe2/YFe2 superlattices
Magnetization and magnetoresistance measurements are reported for antiferromagnetically coupled DyFe2/YFe2 multilayers in fields up to 23 T. It is demonstrated that the formation of short exchange springs ( ~20 Ã…) in the magnetically soft YFe2 layers results in a giant magnetoresistance as high as 32% in the spring region. It is shown that both the magnitude of the effect and its dependence on magnetic field are in good agreement with the theory of Levy and Zhang for domain wall induced giant magnetoresistance