Ultra-high resistive and anisotropic CoPd–CaF2 nanogranular soft magnetic films prepared by tandem-sputtering deposition

Autor: Nobukiyo Kobayashi, Iwasa Tadayoshi, Shigehiro Ohnuma, Ken Ichi Arai, Hiroshi Masumoto, Masayuki Naoe
Rok vydání: 2015
Předmět:
Zdroj: Journal of Magnetism and Magnetic Materials. 391:213-222
ISSN: 0304-8853
DOI: 10.1016/j.jmmm.2015.04.103
Popis: Ultra-high resistive and anisotropic soft magnetic films for gigahertz applications are desirable to demonstrate the really practical films. Here we present a study of novel nanogranular films fabricated by tandem-sputtering deposition. Their electromagnetic properties and nanostructure have also been discussed. These films consisted of nanocrystallized CoPd alloy-granules and CaF2 matrix, and a specimen having a composition of (Co0.69Pd0.31)52–(Ca0.31F0.69)48 exhibited distinct in-plane uniaxial anisotropy after uniaxial field annealing with granule growth. Its complex permeability spectra have a ferromagnetic resonance frequency extending to the Super-High-Frequency band due to its higher anisotropy field, and its frequency response was quite well reproduced by a numerical calculation based on the Landau–Lifshitz–Gilbert equation. Furthermore, it was clarified that the CaF2-based nanogranular film exhibits a hundredfold higher electrical resistivity than conventional oxide or nitride-based films. Higher resistivity enables the film thickness to achieve a margin exceeding threefold against eddy current loss. The greater resistivity of nanogranular films is attributed to the wide energy bandgap and superior crystallinity of CaF2 matrix.
Databáze: OpenAIRE
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