Giant magnetoimpedance

For comparison, in normal electrical conductors the effect of the skin-depth becomes important for frequencies in the microwave range only.

It includes an alternating current source, a phase sensitive amplifier for detecting the ac voltage across the sample and an electromagnet for applying a dc magnetic field.

[6][7] These initial studies were limited to frequencies of a few hundreds of Hz and the changes of impedance reported in those works were not large.

Starting in the 1990s, this phenomenon was investigated again, this time making use of currents with frequencies of hundreds of kHz.

[9] Due to the high sensitivity of the sensors using the GMI effect, they have been used in compasses, accelerometers, virus detection, biomagnetism, among other applications.

Typical experimental set-up for measuring the GMI (inset) and GMI data for a FeZr alloy at 150 K (From ref. 4).
In-phase component of the GMI measured for a piece of an amorphous ferromagnetic material (From ref. 7)