EFFECT OF SUBSTITUTION OF METAL IONS AT Mn-SITE IN La_(0.7)Ca_(0.3)MnO_3: THE MAJOR ROLE OF CHARGE, SPIN, IONIC RADII AND LATTICE PARAMETER

摘要

The manganite system highlights wide range of remarkable properties on merely doping the host compound to change charge density, magnetic coupling, the nature of the ground state, and the effect of interfacial magnetic polarization. We have systematically studied the effect of transition metal ions (V, Ti, Cr, Fe, Co, Ni, Cu, Zn) doping (with fixed 5% concentration) in the Mn lattice sites in La_(0.7)Ca_(0.3)MnO_3 (LCMO) which will modify the double exchange interaction, heart of transport mechanism in these systems and will give better understanding of underlying mechanisms. The variation in the metal-insulator transition temperature (Tp), the Curie temperature (Tc) and the maximum value of magnetoresistance (MR) with respect to lattice parameter and the ionic radii of dopants, was examined. The concentration dependence of these properties was probed by Fe doping (0 < x < 0.05) and isomorphous substitution of Al~(3+) ions (0 < x < 0.05) at Mn-site.