Thermal conductivity in the ferromagnetic metallic phase of monovalent Ag doped manganites

Abstract

The thermal conductivity (κ) behavior in La 0.75 Ag 0.25 MnO 3 manganites is investigated by probing the phonon, carrier and magnon scattering sources. The acoustic phonon contribution to the thermal conductivity (κph) is investigated within the Debye-type relaxation rate approximation. The scattering of phonon from defects, grain boundaries, charge carriers, and phonon are the major sources. La 0.75 Ag 0.25 MnO 3 witnesses the dominant κph and is artifact of strong phonon–impurity and phonon–phonon scattering mechanism in the ferromagnetic metallic state. The carrier contribution to the thermal conductivity (κe) is estimated following the Wiedemann–Franz law. In the metallic phase spin waves (κm) also shows the importance. It is noticed that κm increases with a T2 dependence on the temperature. The behavior of thermal conductivity (κ) in La 0.75 Ag 0.25 MnO 3 is determined by competition among the several operating scattering mechanisms for the heat carriers and a balance between electron, magnon, and phonon contributions.