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Extrinsic magnetoresistance near room temperature in the La-Ca manganites doped with Cu

M.-L. CRAUS1,2, M. LOZOVAN2,* , C. BACIU3

Affiliation

  1. Joint Institute for Nuclear Research-Laboratory of Neutron Physics, Dubna, Joliot-Curie 6, 141980 Dubna, Region Moskva, Russia
  2. National Institute of R&D for Technical Physic s- IFT, Iasi, 47, Mangeron Blvd. Iasi, Romania
  3. ”Gh. Asachi” University, 11 Carol I Boulevard, 700050, Iasi, Romania

Abstract

The La1-xCaxMn0.9Cu0.1O3 perovskites were sintered by means of standard ceramic technology. The final sintering took place between 1100 and 1200oC in air. The sintered samples were analysed with a STOE (Guinier type) diffractometer, by using CuKα1 radiation. The position of the cations and anions in the unit cell, the average size of the coherent blocks and the microstrains were obtained by means a Rietveld program. The variation specific magnetization with temperature was determined with a Foner type magnetometer, between 77 and 400 K, while the transport properties were performed between 300 and 450 K. The investigated compounds have an orthorhombic structure (Pbnm, SG 62), with an increase of the lattice constants with the La concentration in the samples. The average radii of A and B places (rA and, respectively, rB) increase with the La3+ concentration, while the increase of the oxygen concentration leads to a decrease of rB. The microdistorstions exhibt a dependence on the sintering conditions. We proposed a model which explains the observed variation of the transport behavior of the investigated manganites..

Keywords

Extrinsic magnetoresistance, Crystalline and magnetic structure, La-Ca manganites.

Submitted at: Nov. 14, 2006
Accepted at: May 15, 2007

Citation

M.-L. CRAUS, M. LOZOVAN, C. BACIU, Extrinsic magnetoresistance near room temperature in the La-Ca manganites doped with Cu, Journal of Optoelectronics and Advanced Materials Vol. 9, Iss. 5, pp. 1582-1585 (2007)