INFLUENCE OF A 36.8-DEGREES GRAIN-BOUNDARY ON THE MAGNETORESISTANCE OF LA0.8SR0.2MNO3-DELTA SINGLE-CRYSTAL FILMS

Epitaxial ferromagnetic manganite films have been sputtered on bicryst al substrates. Their magnetoresistance was measured as a function of m agnetic field and temperature. The grain boundary magnetoresistance at low temperature is separated from the intrinsic magnetoresistance nea r the Curie temperature. The grain boundary magnetoresistance peaks at about 100 Oe and saturates at about 2 kOe. For a La0.8Sr0.2MnO3 film with a grain boundary angle theta = 36.8 degrees a field independent c omponent r(0) = 4.1 x 10(-6) Omega cm(2) was separated from a field-de pendent component which has its maximum r(H) = 2.3 x 10(-6) Omega cm(2 ) for H of order the coercive field. (C) 1997 American Institute of Ph ysics.