Articles you may be interested inGiant magneto-impedance effect in amorphous ferromagnetic wire with a weak helical anisotropy: Theory and experimentThe extraordinarily high ͑up to 800% magnetoimpedance ratio͒ 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 %/Oe͒ 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.

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The magnetization process and the magnetic domains of the FeNi (100 nm)/Cu (2.5 nm)/FeNi (100 nm)/Cu (480 nm)/FeNi (100 nm)/Cu (2.5 nm)/FeNi (100 nm) structure were studied. This geometry consists of two FeNi/Cu/FeNi trilayers with a thick in the direction perpendicular to the plane of the sensitive element and narrow in the direction of the flowing current Cu electrode in the centre. Ferromagnet/conductor/ferromagnet is the typical geometry of magnetoimpedance thin-film-based sensitive elements used to detect small magnetic fields. Multilayered structures were prepared by rf-sputtering in a magnetic field of 100 Oe applied perpendicular to the Cu electrode in order to induce transverse magnetic anisotropy. The magnetic measurements and magnetic domain structure observations were made in magnetic fields applied one at a time parallel or perpendicular to the Cu electrode. Different magnetization processes with non-homogeneous rotations in the first case and dominant multiple nucleation and merging of domains in the second one were observed.

Articles you may be interested inTunable asymmetric magnetoimpedance effect in ferromagnetic NiFe/Cu/Co films Appl. Phys. Lett. 105, 102409 (2014); 10.1063/1.4895708 Magnetoimpedance and magnetization processes of FeCoNi electroplated tubesVery large magnetoimpedance effect in FeCoNi ferromagnetic tubes with high order magnetic anisotropy Magnetoimpedance effect in CoFeNi plated wire with ac field annealing destabilized domain structure A giant magnetoimpedance effect ͑GMI͒ has been measured in a CuBe 0.1 mm diameter wire, electroplated with a Co 6 Fe 20 Ni 74 layer 1 m thick. Heat treatments after the electrodeposition were performed under the dc or ac field. The GMI has been measured in the frequency range 0.25 to 9 MHz, using ac driving current from 5 to 35 mA. The maximum GMI ratio depends strongly on the heat treatments, the intensity and the frequency of the driving current, reaching the value of 165% for optimal conditions. Results are discussed, taking into account the anisotropy distribution in the magnetic layer induced by the heat treatments under the field and a simple rotation model.

Articles you may be interested inVery large magnetoimpedance effect in FeCoNi ferromagnetic tubes with high order magnetic anisotropy