Heat transport as a probe of electron scattering by spin fluctuations: the case of antiferromagnetic CeRhIn(5).

Heat and charge conduction were measured in the heavy-fermion metal CeRhIn(5), an antiferromagnet with T(N)=3.8 K. The thermal resistivity is found to be proportional to the magnetic entropy, revealing that spin fluctuations are as effective in scattering electrons as they are in disordering local moments. The electrical resistivity, governed by a q(2) weighting of fluctuations, increases monotonically with temperature. In contrast, the difference between thermal and electrical resistivities, characterized by a omega(2) weighting, peaks sharply at T(N) and eventually goes to zero at a temperature T(*) approximately = 8 K. T(*) thus emerges as a measure of the characteristic energy of magnetic fluctuations.