Pulsed laser deposition and thermal characterization of Ni-doped La5Ca9Cu24O41 thin films

Highly b-axis oriented polycrystalline Ni-doped La5Ca9Cu24O41 thin films have been grown on (0 0 1) SrTiO3 substrates using the pulsed laser deposition technique. EDX measurements have revealed nearly stoichiometric target-to-film transfer of Ni concentration up to 6.6 at.%. The 3ω method has been employed to carry out thermal conductivity measurements in the range 90-300 K. The results indicate that the out-of-plane thermal conductivity (κb) decreases with increasing Ni doping level. The temperature dependence of κb observed in pristine and Ni-doped films is similar to that observed in polycrystalline pellets indicating that the grain boundaries play a significant role in the heat transport.