Electronic and magnetic states in metallic compounds-I. Kondo effect and ferromagnetism in CoAl

D. J. Sellmyer, G. R. Caskey, J. Franz

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Abstract

Magnetic susceptibility and electron transport properties were investigated in CoAl alloys in the vicinity of exact stoichiometry. Resistance minima, negative magnetoresistance, and thermo-power anomalies were observed in the liquid helium region. The concentration, temperature, and field dependence of the transport properties were interpreted in terms of localized magnetic moments formed on Co atoms on Al sites (Cox atoms) in the lattice. The effective moment on the Cox atoms in the paramagnetic state is 5·9 μR. Analysis of the data in terms of the theories of the Kondo effect led to estimates of the exchange parameter and Kondo temperature of ∼ -1·3 to -2·2 eV and ∼8°K. respectively. At excess Co concentrations of more than 0·6 at.%. ferromagnetic interactions between the Cox atoms become apparent in that the resistance minima disappear, the Weiss temperature changes from negative to positive, and remanent magnetization is observed. The nature of the ferromagnetic state is discussed along with some evidence for spin-fluctuation effects in the nearly ferromagnetic alloys.

Original languageEnglish (US)
Pages (from-to)561-576
Number of pages16
JournalJournal of Physics and Chemistry of Solids
Volume33
Issue number3
DOIs
StatePublished - 1972

Fingerprint

Kondo effect
Metallic compounds
Coal
Ferromagnetism
coal
ferromagnetism
Atoms
electronics
atoms
transport properties
Electron transport properties
Spin fluctuations
Helium
Magnetoresistance
Magnetic moments
Magnetic susceptibility
liquid helium
Stoichiometry
Transport properties
Temperature

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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Electronic and magnetic states in metallic compounds-I. Kondo effect and ferromagnetism in CoAl. / Sellmyer, D. J.; Caskey, G. R.; Franz, J.

In: Journal of Physics and Chemistry of Solids, Vol. 33, No. 3, 1972, p. 561-576.

Research output: Contribution to journalArticle

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N2 - Magnetic susceptibility and electron transport properties were investigated in CoAl alloys in the vicinity of exact stoichiometry. Resistance minima, negative magnetoresistance, and thermo-power anomalies were observed in the liquid helium region. The concentration, temperature, and field dependence of the transport properties were interpreted in terms of localized magnetic moments formed on Co atoms on Al sites (Cox atoms) in the lattice. The effective moment on the Cox atoms in the paramagnetic state is 5·9 μR. Analysis of the data in terms of the theories of the Kondo effect led to estimates of the exchange parameter and Kondo temperature of ∼ -1·3 to -2·2 eV and ∼8°K. respectively. At excess Co concentrations of more than 0·6 at.%. ferromagnetic interactions between the Cox atoms become apparent in that the resistance minima disappear, the Weiss temperature changes from negative to positive, and remanent magnetization is observed. The nature of the ferromagnetic state is discussed along with some evidence for spin-fluctuation effects in the nearly ferromagnetic alloys.

AB - Magnetic susceptibility and electron transport properties were investigated in CoAl alloys in the vicinity of exact stoichiometry. Resistance minima, negative magnetoresistance, and thermo-power anomalies were observed in the liquid helium region. The concentration, temperature, and field dependence of the transport properties were interpreted in terms of localized magnetic moments formed on Co atoms on Al sites (Cox atoms) in the lattice. The effective moment on the Cox atoms in the paramagnetic state is 5·9 μR. Analysis of the data in terms of the theories of the Kondo effect led to estimates of the exchange parameter and Kondo temperature of ∼ -1·3 to -2·2 eV and ∼8°K. respectively. At excess Co concentrations of more than 0·6 at.%. ferromagnetic interactions between the Cox atoms become apparent in that the resistance minima disappear, the Weiss temperature changes from negative to positive, and remanent magnetization is observed. The nature of the ferromagnetic state is discussed along with some evidence for spin-fluctuation effects in the nearly ferromagnetic alloys.

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