10 research outputs found
Magnetization reversal process and nonlinear magneto-impedance in Cu/NiFe and Nb/NiFe composite wires
The magnetization reversal of Cu/NiFe and Nb/NiFe composite wires carrying AC
current is studied. The frequency spectrum of a voltage induced in a pick-up
coil wound around the wire is analyzed. The frequency spectrum is shown to
consist of even harmonics within a wide range of AC current amplitudes and
longitudinal DC magnetic fields. The strong dependencies of the harmonic
amplitudes on the DC field are found. The results obtained may be of importance
for the design of weak magnetic field sensors.Comment: 8 pages, 4 figures, publishe
Modeling of asymmetric giant magnetoimpedance in amorphous ribbons with a surface crystalline layer
A model describing the asymmetric giant magnetoimpedance (GMI) in
field-annealed amorphous ribbons is proposed. It is assumed that the ribbon
consists of an inner amorphous core and surface hard magnetic crystalline
layers. The model is based on a simultaneous solution of linearizied Maxwell
equations and Landau-Lifshitz equation. The coupling between the surface layers
and the amorphous core is described in terms of an effective bias field.
Analytical expressions for the frequency and field dependences of the ribbon
impedance are found. The calculated dependences are in a qualitative agreement
with results of experimental studies of the high-frequency asymmetric giant GMI
in field-annealed amorphous ribbons.Comment: 13 pages, 3 figure
The effect of stripe domain structure on dynamic permeability of thin ferromagnetic films with out-of-plane uniaxial anisotropy
The permeability is calculated for a thin ferromagnetic film with the stripe
domain structure and out-of-plane uniaxial magnetic anisotropy. Analytical
expressions for the frequency dependence of components of permeability tensor
are derived with the use of the Smit-Beljers method, with the thickness of
domain walls and the domain wall motion being neglected. The effect of the
domain width and the angle between the anisotropy axis and the film plane on
the frequency dependence of the permeability is analyzed. General equations
relating the static permeability components and the ferromagnetic resonance
frequencies are found. The results of the approach are applied to the
derivation of the constraint for the microwave permeability of thin
ferromagnetic films. The analysis of the constraint as a function of the axis
deviation angle, the domain aspect ratio and the damping parameter allows the
conditions to be found for maximal microwave permeability. The results obtained
may be useful in connection with the problem of developing high-permeable
microwave magnetic materials.Comment: 22 pages, 6 figure
Current distribution and giant magnetoimpedance in composite wires with helical magnetic anisotropy
The giant magnetoimpedance effect in composite wires consising of a
non-magnetic inner core and soft magnetic shell is studied theoretically. It is
assumed that the magnetic shell has a helical anisotropy. The current and field
distributions in the composite wire are found by means of a simultaneous
solution of Maxwell equations and the Landau-Lifshitz equation. The expressions
for the diagonal and off-diagonal impedance are obtained for low and high
frequencies. The dependences of the impedance on the anisotropy axis angle and
the shell thickness are analyzed. Maximum field sensitivity is shown to
correspond to the case of the circular anisotropy in the magnetic shell. It is
demonstrated that the optimum shell thickness to obtain maximum impedance ratio
is equal to the effective skin depth in the mahnetic material.Comment: 23 pages, 7 figure
Giant magnetoimpedance in composite wires with insulator layer between non-magnetic core and soft magnetic shell
10.1016/j.jmmm.2005.10.149Journal of Magnetism and Magnetic Materials3001e63-e66JMMM