HOPPING CONDUCTIVITY OF MAGNETIC POLARONS IN EPITAXIAL PR0.5SR0.5MNO3FILMS

We present data on tile electrical transport and negative magnetoresis tivity effect in epitaxial films of Pr0.5Sr0.5MnO3, which undergoes tw o magnetic phase transitions, both accompanied by apparent changes in tile conductive mechanism. It is shown that conductivity arises from h opping processes, while tile giant negative magnetoresistivity seems t o be of a similar origin in the ferro- and in the antiferromagnetic ph ase.