Thermal conductivity of giant magnetocaloric Mn compounds

Abstract

Temperature dependence of the thermal conductivity of Mn1.03As0.70Sb0.30 and Ru-doped or Ni-doped (MnFeRu)2(PSi) was studied. These compounds undergo a first-order magnetic transition (FOMT) near room temperature and exhibit a giant magnetocaloric effect at around the Curie temperature. The thermal conductivity of Ru-doped and Ni-doped compounds is abruptly reduced at the Curie temperature during the first cooling. This is due to the micro-cracks generated during the FOMT. On heating, the thermal conductivity shows positive temperature dependence. The Ru-doped and Ni-doped compounds show small humps in the temperature dependence of the thermal conductivity near TC. The thermal conductivity of ferromagnetic metals is given by the sum of the phonon component, the electronic component, and the magnetic component. The results are discussed by taking account of the temperature dependence of each component.