Neutron irradiation effect on permeability and magnetoimpedance of amorphous and nanocrystalline magnetic materials

Abstract

In this paper we provide physical insights into the effect of neutron irradiation on permeability spectra and magnetoimpedance of amorphous and nanocrystalline alloys. Experimental results indicate that neutron irradiation increases the permeability of the amorphous alloy but decreases the permeability of the nanocrystalline alloy in a high frequency region ͑f ജ 1 MHz͒, while the opposite is found in a low frequency region ͑f Ͻ 1 MHz͒. A careful examination of sample temperature during neutron irradiation process excludes thermal annealing as a possible origin of the observed irradiation effect. The magnetic relaxations in the low and high frequency regions are ascribed to the irreversible domain wall motion and reversible rotational magnetization, respectively. The enhancement in the permeability of the amorphous alloy upon neutron irradiation leads to a parallel improvement of magnetoimpedance response of the material, which is of practical use for sensing applications.

Optimization of magnetoimpedance effect in Co-based ribbon by laser patterning for sensor arrays application

“…Therefore, the adjustment of δ m trough σ, µ t , saturation magnetization M s , ferromagnetic relaxation parameter α and surface roughness is the most popular topics. Efforts have been made to adjust δ m by annealing treatment [4][5][6][7][8], stress [9][10][11], neutron irradiation [12,13], surface coating or polishing [14][15][16][17][18][19][20] and cryogenic treatment [21][22][23][24]. On the other hand, the complex impedance of a ribbon can be expressed as follows [25,26]:…”

Magnetization dynamics of FeCuNbSiB soft magnetic ribbons and derived powder cores

“…The complex permeability spectroscopy [2] is a very useful method for systematic study of AC magnetization behaviour of ferromagnets, which was used for a wide variety of traditional and modern materials, e.g. electric steels [1,5], magnetic wires [6][7][8], ferrites [3,[9][10][11][12], amorphous and nanocrystalline alloys [2,[13][14][15][16][17][18][19][20][21] with a lot of various compositions. Many efforts of scientists have been made to describe the different effects of the various thermal annealing treatment conditions [13][14][15], the changes in nominal compositions [16,17], neutron irradiation [20], surface corrosion [21] and many others on the magnetization mechanisms in soft magnetic alloys by using the complex permeability.…”