Transport and magnetic properties of La1-xCaxMnO3-films (0.1 x 0.9)

By laser ablation we prepared thin films of the colossal magnetoresistive c ompound La1-xCaxMnO3 with doping levels 0.1 < x < 0.9 on MgO substrates. X- ray diffraction revealed epitaxial growth and a systematic decrease of the lattice constants with doping. The variation of the transport and magnetic properties in this doping series was investigated by SQUID magnetization an d electrical transport measurements. For the nonmetallic samples resistance s up to 10(13) Omega have been measured with an electrometer setup. While t he transport data indicate polaronic transport for the metallic samples abo ve the Curie temperature the low-doped ferromagnetic insulating samples sho w a variable range hopping like transport at low-temperature. (C) 2000 Else vier Science B.V. All rights reserved.