Giant magnetic field dependent impedance of amorphous FeCoSiB wire

TLDR

The impedance of a 100 µm diameter Fe4.3Co68.2Si12.5B15 amorphous wire shows a very large frequency‑dependent resistance in addition to its known frequency‑dependent reactance. The study aims to quantitatively analyze the giant magnetic field dependent impedance of the wire. The analysis is based on classical electrodynamics. The impedance’s frequency response is almost entirely suppressed by an axial magnetic field HA<150 Oe, yielding a magnetoresistance of ΔR/Rsat = 370 % at 1 MHz, with the bulk of the magnetic response occurring for HA<5 Oe, indicating strong technological promise.

Abstract

The impedance of an amorphous Fe4.3Co68.2Si12.5B15 wire (100 μm diameter) exhibits an extraordinarily large frequency dependent resistance in addition to the previously reported frequency dependent wire reactance. The frequency response of both the resistance and reactance is almost entirely suppressed by an axial magnetic field HA&amp;lt;150 Oe, resulting in a typical magnetoresistance for frequencies f&amp;lt;1 MHz of the order of the dc wire resistance. The magnetoresistance at f=1 MHz is ΔR/Rsat=370%. As the bulk of the magnetic response occurs for HA&amp;lt;5 Oe, this system shows great technological promise. We give a quantitative analysis of the phenomenon, which is rooted in classical electrodynamics.