Seminars Archive

Synthesis and Properties of Magnetoresistive Perovskite Materials

Abstract
This talk will focus on synthesis, structural, magnetic and electronic transport properties of magnetoresistive perovskite materials. Materials exhibiting colossal magnetoresistance (CMR) undergo a large change in electrical resistance in response to an external magnetic field. A range of compounds have now been found to exhibit intrinsic CMR, notably La0.7Sr0.3MnO3 and Sr2FeMoO6. The potential applications for these materials include non-volatile magnetic random access memory (MRAM), magnetic read heads for hard drives and a variety of other magnetic sensor applications. We have investigated the effects of A-cation size variance and substitution of Mg and Nb on magnetic and magneto-transport properties of Sr2FeMoO6 double perovskite and some of the interesting results will be presented in this talk. In a search for new CMR materials, we have also prepared two new Ruddlesden-Popper phase analogues of Sr2FeMoO6: Sr4FeMoO8 and Sr3FeMoO7 and they have been characterized by the neutron diffraction and magnetic and electronic transport properties measurements. Both materials show ferromagnetic hysteresis loops at 5 K with saturated moments of 0.8 mB and 0.2 mB for Sr3FeMoO7 and Sr4FeMoO8, respectively. The results of powder neutron diffraction, and magnetic and electronic transport measurements on a large number of RBaMnFeO6-x (R = La, Pr, Nd and Tb) perovskites and RuSr2(Ce0.95-xNd0.85+x)Y0.2Cu2O10 ruthenocuperates will also be presented here. Ruthenocuperates are known for their superconducting properties but for the first time we have reported a large CMR effect of ~45% in these materials.