Effects of chromium ion implantation on the magneto-transport properties of La_(0.7)Ca_(0.3)MnO_3 thin films

摘要

Thin films of colossal magnetoresistance material La_(0.7)Ca_(0.3)MnO_3 were implanted with different fluence 200keV Cr ions. Resistivty measurements in zero and applied fields of up to 8T were made in order to determine the effects of the implanted magnetic ions on the magnetoresistance (MR). As the Cr fluence was increased, the resistivity increased and the metal-insulator transition (MI) temperature was suppressed to values below the experimentally accessible temperature range as a result of oxygen loss and the creation of defects. However, for the highest fluence of 5x10~(15) ions/cm~2, a re-entrant metal-insulator type transition was observed. Furthermore a significant improvement in the low field MR was observed for fields less than 500mT. These results are interpreted in terms of subtitution of Cr ions onto Mn sites and the creation of a magnetically inhogeneous material and the influence of oxygen deficiency.