Very Large Magnetoimpedance Effect in FeCoNi Ferromagnetic Tubes with High Order Magnetic Anisotropy

Abstract

The extraordinarily high (up to 800% magnetoimpedance ratio) and sensitive magnetoimpedance effect has been found and studied in FeCoNi magnetic tubes electroplated onto CuBe nonmagnetic wire at frequency of about 1 MHz order. Special annealing was done in order to induce magnetic anisotropy. The high harmonic response has been studied, and the harmonics show larger variations with the external magnetic field than the fundamental. This huge sensitivity of the harmonics (up to an order of the tens of thousands %/Oe) is promising in regard to the increase of the sensitivity of giant magnetoimpedance sensors. To explain the experiment results, we calculated the high frequency transverse susceptibility taking into account the magnetic anisotropy of first and second orders. The susceptibility is extremely high at the points of orientational phase transitions in the magnetic layer which gives rise to strong nonlinear effects. © 2001 American Institute of Physics.