Abstract
Temperature-dependent transport and magnetic measurements on Sr2Y0.5Ca0.5Co2O7 indicate that ferromagnetism appears along with a crossover between two forms of variable-range-hopping (VRH) conductivity on cooling. Efros-Shklovskii (ES)-type VRH conduction was found below approximately 30 K, transformed from Mott-type VRH at higher temperature. The magnitude of the Coulomb gap and the Mott-ES VRH crossover temperature are ∼57 K and ∼170 K, respectively. These are unusually large compared to those of nonmagnetic disordered materials. The peculiar electronic state for the ferromagnetic Coulomb gap is probably due to Coulomb correlations among d electrons in the disordered system.
Original language | English (US) |
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Journal | Physical Review B - Condensed Matter and Materials Physics |
Volume | 63 |
Issue number | 6 |
DOIs | |
State | Published - Jan 10 2001 |
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics