Absence of the ordinary and extraordinary Hall effects scaling in granular ferromagnets at metal-insulator transition

D. Bartov, A. Segal, M. Karpovski, A. Gerber

Research output: Contribution to journalArticlepeer-review

Abstract

Universality of the extraordinary Hall effect scaling was tested in granular three-dimensional Ni-SiO2 films across the metal-insulator transition. Three types of magnetotransport behavior have been identified: metallic, weakly insulating, and strongly insulating. Scaling between both the ordinary and the extraordinary Hall effects and material's resistivity is absent in the weakly insulating range characterized by logarithmic temperature dependence of conductivity. The results provide compelling experimental confirmation for recent models of granular metals predicting transition from logarithmic to exponential conductivity temperature dependence when intergranular conductance drops below the quantum conductance value and loss of Hall effect scaling when intergranular conductance is higher than the quantum one. The effect was found at high temperatures and reflects the granular structure of the material rather than low-temperature quantum corrections.

Original languageEnglish
Article number144423
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume90
Issue number14
DOIs
StatePublished - 17 Oct 2014

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