Thermal and thermoelectric properties of granular Co-Ag solids
Abstract
We report measurements on the temperature and magnetic field dependences of the thermal conductivity, thermoelectric power, and specific heat of granular Co 20Ag 80 solids annealed at various temperatures. Giant magnetothermal conductivity and giant magnetothermopower are found to be correlated with the giant magnetoresistance. Thermal conductivity is dominated by its electronic contribution, and the Wiedemann-Franz law is found to be satisfied between 2 and 300 K, indicating that large-angle electron scattering processes dominate. The thermoelectric power is negative and its magnitude is considerably reduced by the annealing process. The contrasting relationship between electrical resistivity and thermoelectric power on annealing and in applied field is curved and discussed. No marked variation of specific heat with magnetic field in relation to the giant magnetoresistance has been observed. At very low temperatures, i.e. below T ∼ 1 K, a nuclear contribution to the specific heat appears, whose temperature and magnetic field dependences have been explored.
- Publication:
-
Journal of Magnetism and Magnetic Materials
- Pub Date:
- September 1994
- DOI:
- 10.1016/0304-8853(94)90468-5
- Bibcode:
- 1994JMMM..136..221P