ION-IMPLANTATION INDUCED ENHANCEMENT OF MAGNETORESISTANCE IN LA0.67CA0.33MNO3

Thin films of colossal magnetoresistance (MR) material, La0.67Ca0.33Mn O3, were implanted with different doses (10(11)-10(15) ions/cm(2)) of 200 keV Ar+ ions. The implanted samples were examined by ion channelin g and x-ray diffraction techniques. The channeling results clearly sho wed that the magnitude of the induced lattice disorder did not increas e greatly for implantation doses up to 5x10(13) ions/cm(2) In this low dose implantation regime, the magnetoresistance {MR=[R(O)-R(H)]/R(O)} increased by 50%, the peak resistivity went up by two orders of magni tude, and the magnetoresistivity peak temperature decreased by 130 K c ompared to the original, unimplanted sample. For doses greater than or equal to 5x10(13) ions/cm(2), the damage was significant and caused t he sample to become semiconducting. (C) 1996 American Institute of Phy sics.