Magnetic and transport properties of granular cobalt films

S. Barzilai*, Y. Goldstein, I. Balberg, J. S. Helman

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

108 Scopus citations

Abstract

Simultaneous magnetization and magnetoresistance measurements have yielded the magnetic phase diagram of the granular Co-SiO2 system. The superparamagnetic-to-ferromagnetic transition temperature changes gradually with composition from 80 K at 20 vol% Co to 280 K at 43 vol% Co. The results confirm the theory of spindependent tunneling in granular magnetic metals and yield the value of JP=(1.0±0.3) meV. Here P is the spin polarization of the tunneling electrons and J their exchange-coupling constant. This quantity has not been measured previously for cobalt. A quantitative comparison shows that the molecular-field theory does not provide an adequate description of the magnetization of granular cobalt.

Original languageEnglish
Pages (from-to)1809-1817
Number of pages9
JournalPhysical Review B
Volume23
Issue number4
DOIs
StatePublished - 1981

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