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A fast fault current limiter based on La0.67Ca0.33MnO3films and designed in the shape of a co-planar 50 Ω impedance transmission line is presented. The limiter is intended to protect the input circuits of high frequency wide band electronic devices. The operation of this limiter is based on fast electroresistance phenomenon in manganites. The main behaviour of this phenomenon at temperatures close to its phase transition temperature Tmwas studied. It was demonstrated that the specific resistance of the film decreases exponentially with increase of electric field. The experimental results of losses induced by the fault current limiter in a 50 Ω impedence transmission line for non-limiting and limiting regimes are presented. The phenomenological relation between input and output voltage transients' amplitudes of transmission lines protected by such limiter is obtained.

Thin films of La0.7Sr0.3MnO3grown on (001) NdGaO3substrate using vertical hot wall Injection CVD reactor were investigated by means of standard fish-bellied beam inducing uniaxial compressive (or tensile) strain of the films. The measurements were carried out in current direction both parallel (longitudinal resistance R1) and perpendicular (transversal resistance R1) to the strain direction. The compression along [100], [110], [010] and [110] directions on films having 8 nm thickness showed the strong anisotropy of strain induced resistance change. The compression along [010] and [l10] directions caused the decrease of the film resistance while the compression along [100] and [110] directions increased this resistance. The maximum obtained relative resistance change was about 27% at strain 0.005. This effect appeared in both longitudinal and transversal directions of the electric current. The experimental results are discussed in terms of external strain influence on anisotropically strained La0.7Sr0.3MnO3film lattice produced as a result of large mismatch between substrate and film lattice constants.