Thermal conductivity of La 0.67(Ca xSr 1− x) 0.33MnO 3 ( x=0, 0.5, 1) and La 0.6Y 0.07Ca 0.33MnO 3 pellets between 10 and 300 K

Abstract

Thermal conductivity ( λ) of nanocrystalline La 0.67(Ca x Sr 1− x ) 0.33MnO 3 ( x=0, 0.5, 1) and La 0.6Y 0.07Ca 0.33MnO 3 pellets prepared by a novel ‘pyrophoric’ method have been studied between the temperature range 10 and 300 K. Our data show that the magnitude of thermal conductivity is strongly influenced by the ion substitutions at La-site. The analysis of the thermal conductivity data indicates that the thermal transport is governed largely by phonons scattering in these systems and the electronic contribution is as small as 0.2–1% of total thermal conductivity ( λ total). At low temperatures (<90 K) 2D like lattice defects contribute to the phonon scattering dominantly and its strength increases with increasing Sr content and also with partial substitution of La by Y. Depending upon the composition of the samples, the magnon thermal conductivity contributes 2–15% of λ total close to T C. In the paramagnetic regime the unusual increase in λ total keeps signature of large dynamic lattice distortion.