MAGNETIC TRANSITIONS AND MAGNETOTRANSPORT IN EPITAXIAL PR0.5SR0.5MNO3THIN-FILMS

Epitaxial thin films of tile magnetic perovskite Pr0.5Sr0.5MnO3 were p repared by dc-magnetron sputtering, structurally characterized by x-ra y diffraction and their physical properties investigated by magnetizat ion and electrical transport measurements. Ferromagnetic ordering appe ars in zero-field at 263 K, followed hy a second transition into an an tiferromagnetic state at 160 K. The zero-field resistivity has a semic onducting behaviour according to Mott's law and becomes quasi-metallic only within the ferromagnetic state, whose temperature range call be extended by applying an external magnetic field. The negative magnetor esistance effect increases systematically with decreasing temperature and reaches a value of 700 % at 1.5 K in a field of 12 T. For temperat ures below 75 K we observed additionally a memory effect, showing up a s a persistent, field induced lowering of sample resistivity.