Epitaxial thin films of magnetic perovskites - preparation, properties andpossible applications

Doped La-manganites belong to the class of perovskite materials showing the so-called colossal magnetoresistance effect (CMR) near their Curie tempera ture T-c, which can be varied in a wide range up to 380 K. The magnetoresis tance (MR) ratio of sputtered epitaxial films changes strongly with their T -c from 8000% at 90 K to 35% at 310 K in a field of 1 T. Bicrystalline and polycrystalline films show an additional MR effect below T-c. Whereas the C MR effect is caused by a magnetic phase transition the low-temperature MR e ffects are induced by the transport of spin-polarized carriers across grain boundaries acting as tunneling barriers. The CMR effect is interesting for applications especially in position sensors because of its large dynamic r ange without hysteresis and saturation effects. (C) 2000 Elsevier Science L td. All rights reserved.