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Electronic diagram modification in La0.54Ho0.11Ca0.35Mn1-x(Co/Cr)xO3 manganites

M. L. CRAUS1,2, M. LOZOVAN2,* , N. CORNEI3

Affiliation

  1. Joint Institute of Nuclear Research, Dubna, 141980, Russia
  2. National Institute of R&D for Technical Physics, Iasi, 700050, Romania
  3. ”Al.I. Cuza” University, Iasi, 700506, Romania

Abstract

The substitution of Mn with Co cations produces the segregation of electronic phases (two defective AFM phases) in PrCa manganite doped with Co. Magnetic phase is stabilized by the microstrains induced by the Co cations. We have prepared La0.54Ho0.11Ca0.35Mn1-x(Co/Cr)xO3 manganites by sol-gel method. The samples were monitorized by means of X-ray diffractometry (Cu Kα) at room temperature and XRD data were handled by means of Rietveld type programs. The phase composition and structure (unit cell type and parameters, position of the atoms in unit cell, Mn-O distances and Mn-O-Mn bonds angles, microstrains and average size of mosaic blocks) were determined. Magnetic data (variation of specific magnetization with temperature) were obtained with a Foner type magnetometer between 77 and 500 K, at 1T magnetic field intensity. Transport phenomena (variation of resistivity with temperature and magnetic field intensity) were performed by four probes method between 77 and 300 K. Transport properties, including the resistivity values and the transition temperature from metallic to insulator state strongly depend on the concentration of Co/Cr in the samples. The transition temperature decrease slower for doped with Cr samples as for those doped with Co. We discussed the influence of Co/Cr cations on the electronic phase diagram of the La0.54Ho0.11Ca0.35Mn1-x(Co/Cr)xO3 manganites..

Keywords

Manganites, X-ray diffraction, Magnetic properties, Magnetoresistance.

Submitted at: Sept. 25, 2007
Accepted at: Feb. 18, 2008

Citation

M. L. CRAUS, M. LOZOVAN, N. CORNEI, Electronic diagram modification in La0.54Ho0.11Ca0.35Mn1-x(Co/Cr)xO3 manganites, Journal of Optoelectronics and Advanced Materials Vol. 10, Iss. 2, pp. 348-351 (2008)