Abstract
The electrical resistivity ρ and the thermal diffusivity a of gadolinium have been measured as functions of T in the range 45–400 K. The thermal conductivity λ has been calculated from a and experimental data for the specific-heat capacity, . λ can be analyzed in terms of simple models for the lattice and electronic components above the Curie temperature ≃291.4 K. Below an additional term, identified as a magnon (spin-wave) thermal conductivity , is found. ρ and λ have also been studied as functions of T and P in the range 150–400 K and 0–2.5 GPa. The Lorenz function L=ρλ/T increases by about 20%/GPa under pressure due to a very strong pressure dependence of the lattice thermal conductivity. The pressure coefficients of ρ and λ are -5.1× and 0.22 , respectively, at 300 K (above ), and 0 and 0.16 at 200 K (below ). and the spin-reorganization temperature ≃219 K both decrease under pressure, at the rates -14.0 and -22.0 K/GPa, respectively. Although the magnitude of cannot be accurately calculated from the zero-pressure data for λ, the temperature dependence of dλ/dP allows us to distinguish between several models and assign a value of ≃1.5 W , or 16.0% of λ, at 200 K.
- Received 20 April 1989
DOI:https://doi.org/10.1103/PhysRevB.40.9541
©1989 American Physical Society