Temperature dependence of low-field magnetoresistance in perovskite manganites thin films

Abstract

Polycrystalline thin films of La 0.7Ca 0.3MnO 3 (LCMO) and La 0.7Sr 0.3MnO 3 (LSMO) have been deposited on YSZ(1 0 0), Si(1 0 0)/YSZ and Si(1 1 1)/YSZ substrates by magnetron sputtering or pulsed laser deposition (PLD). Well-pronounced low-field magnetoresistance (LFMR) hysteresis was registered with an MR peak in the vicinity of the coercive field. The high value of local MR sensitivity d(MR) /d H in the vicinity of the peak has to be noted, reaching values up to 0.2%/Oe at 5 K for the La 0.7Ca 0.3MnO 3 samples. The LFMR has been investigated in a wide temperature range up to room temperature. High values of low-field magnetoresistance MR=[( R( H)− R(0)]/ R(0) at room temperatures have been registered for samples Si(1 1 1)/YSZ/LSMO obtained by PLD: MR( T=270 K, H=3 kOe)=−2.6%, MR( T=296 K, H=3 kOe)=−1.4%. The temperature dependence of the thin film LFMR has been compared with that one of thin film and bulk manganites. The physical origin of this dependence has been analyzed in order to obtain a structure suitable for application.