Resistivity minimum and the electronic strongly correlation characteristic for La2/3Sr1/3MnO3 thin film

Low-temperature electrical transport and magnetic properties of La-2/3(Sr,Ca)(1/3)MnO3 films deposited on (0 0 1) LaAlO3 substrate were investigated in fields up to 8 T at temperatures down to 2 K. Both samples show identical electrical transport properties at very low temperatures (T < 10 K), i.e., display a well-defined resistivity minimum. It is worth noting that the transition temperature (T-min) in films is very low, about 5 K. It is lower than the ones of the corresponding polycrystalline samples and the other films. Moreover, the T-min almost does not affect by the external applied magnetic fields up to 8 T. The curves obtained at various fields can be fitted under the framework of the e-e interaction in the strongly correlation systems which is the most plausible explanation to the resistivity minimum in the manganites. Magnetic measurement also indicates the disappearance of the grain boundary's contribution to the electrical transport of our samples. (c) 2007 Elsevier B.V. All rights reserved.