Enhancement of microwave giant magnetoresistance effect in reflected wave

Abstract

The microwave giant magnetoresistance ( μGMR) effect in (CoFe/Cu)/glass structures has been investigated. The measurements were carried out at the frequencies from 26 to 38 GHz in two variants of wave incidence: first, on a metal superlattice and then on a dielectric substrate (variant 1) and vice versa (variant 2). For the substrate of 4 mm in thick at the frequency of 27 GHz, when the substrate thickness equals three-quarters of a wavelength, in variant 2, a sharp increase in μGMR was observed for a reflected wave. In this case, the relative variations of the reflected wave amplitude under the application of a magnetic field reached 44%, whereas, in all other cases, the variations did not exceed 5%–8%. Such a sharp increase in the μGMR effect is associated with both a significant decrease in the reflection coefficient and large magnitude of the magnetoresistance effect in superlattices (CoFe/Cu).