Effect of annealing on torsion giant impedance of Co-rich amorphous wires with vanishing magnetostriction

American Institute of Physics 2002-05-15

Torsion giant impedance (TGI) ratio, (^Z/Z), has been measured in as-cast and annealed (Co0.94Fe0.06)72.5B15Si12.5 amorphous wire. Two-step current annealing has been employed: pre-annealing (550 mA, 2 min) plus current annealing under torsion stress (33 (pi) rad/m, 450 mA, up to tann = 105 min). Pre-annealing results in a drastic increase of (^Z/Z) (from 155% to 260%) and decrease of the asymmetry. The consequent annealing under torsion of pre-annealed sample gives rise to the appearance of significant asymmetry of the TGI. In this case (^Z/Z) has a tendency to achieve rather asymmetric shape with a sharp maximum at certain torsion m. The value of m depends on the time of annealing under torsion and on the applied torsion during the annealing. The asymmetric shape of the (^Z/Z) in as-cast state and after torsion annealing could be ascribed to the spontaneous or induced helical anisotropy, which can be compensated by the application of certain torsion stress. Evolution of (^Z/Z)() and Em () as a function of annealing time reflects the kinetic of the induced magnetic anisotropy.

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English

CTK oai:digital.csic.es:10261/21328
Journal of Applied Physics 91(10): 8426 (2002)
0021-8979
10.1063/1.1447519
1103353902

CSIC
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