Structural, electrical and magnetic properties of Co/sub x/C/sub 1-x/ granular films
| Autor: | Eberhard F. Wassermann, A. Carl, Bernd Rellinghaus, Dieter Weller, H. Weinforth, C. Somsen |
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| Rok vydání: | 1998 |
| Předmět: |
Materials science
Magnetoresistance Annealing (metallurgy) Analytical chemistry Percolation threshold Microstructure Magnetic hysteresis Electron beam physical vapor deposition Electronic Optical and Magnetic Materials Condensed Matter::Materials Science Nuclear magnetic resonance Ferromagnetism Electrical and Electronic Engineering Superparamagnetism |
| Zdroj: | IEEE Transactions on Magnetics. 34:1132-1134 |
| ISSN: | 0018-9464 |
| DOI: | 10.1109/20.706413 |
| Popis: | We report on the structural, electrical and magnetic properties of thin Co/sub x/C/sub 1-x/ granular films with metal volume fraction x=0.27 close to the percolation threshold x/sub p//spl ap/0.3. The granular films are prepared by simultaneous UHV electron beam evaporation of high purity Co and C at room temperature. The structural properties are determined from transmission electron microscopy revealing small Co clusters with mean diameters of about 3 nm randomly dispersed in an electrically insulating C matrix. As-prepared films show insulating resistance behavior. Upon annealing to T/sub a/=600/spl deg/C in-situ measurements within the electron microscope show coalescence of the Co clusters forming continuous cluster-networks. Resistance versus temperature and magnetoresistance measurements on annealed films show a gradual change from insulating to metallic behavior. Room temperature measurements of the magnetic properties show the evolution of ferromagnetic behavior from superparamagnetic behavior upon annealing with a formation of an unusual perpendicular anisotropy. |
| Databáze: | OpenAIRE |
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