Extra high frequency features of nanogranular magnets with GMI

Abstract

The results of research of electromagnetic waves interaction with the promising magnetic nanogranular layered structures in (10, 30 45) GHz frequency bands are presented. We applied the electron spin resonance (ESR) technique to study the magnetic order of nanostructures, which demonstrate the giant magnetic resistance (GMR) effect and the extra high frequency giant magnetic impedance (GMI) effect. The data under discussion are the ESR/FMR-linewidth, -line positions and their variations depending on the temperature. Besides this, the ESR response from the specimen, located in plane or normally to the external magnetic field, has been detected and the magnetization of saturation has been calculated using these data. The nanogranular Co- and Fe-contained specimens, which exhibit the GMI effect (at 30-45 GHz), have been studied. The correlation between the magnetic structure of specimens and GMI magnitude is considered. (C) 2005 Elsevier B.V. All rights reserved.