Comparison of the magnetic and transport properties of Ga-, Ni-, and Fe-doped perovskite manganese oxides

A comparative study on magnetic and transport properties has been performed for B-site substituted perovskites La0.67Sr0.33Mn0.90B0.10O3 (B = Ga, Ni, and Fe). The doped samples show a notable decrease of the Curie Temperature , from 365 K of the undoped sample to 290 K (Ga), 292 K (Ni), and 265 K (Fe ). Furthermore, the metal-semiconductor transition peaks in the doped sampl es shift to lower temperature, from above 300 K (undoped) to 212 K (Ga), 23 7 K (Ni), and 195 K (Fe). This considerable differences in magnetic and tra nsport properties between doped and undoped samples and the diversity among the doped samples can be explained by the destruction of the partial doubl e-exchange interactions and the exchange couplings between Mn and doped ion s. (C) 1999 American Institute of Physics. [S0021-8979(99)04420-5].