Coexistence and competition of ferromagnetic and charge ordered phases in strained La1−xCaxMnO3 films

Magnetotransport properties of thin films of La1−xCaxMnO3 (x=0.3; 0.51) deposited on LaAlO3 and SrTiO3 substrates were investigated. Compressively strained La0.7Ca0.3MnO3 layers reveal semiconducting behaviour and charge ordered insulating (COI) phase which melts to ferromagnetic metallic (FMM) above a certain magnetic field, accompanied by a significant hysteresis. The La0.49Ca0.51MnO3 samples possess stable COI state. Variable range Hopping mechanism well describes the conductance in zero magnetic field. Magnetotransport properties of strained thin films are consistent with the phase segregation model, i.e. with the coexistance and competition of COI and FMM phases.