| Popis: |
Nanocrystalline A-doped manganites, with compositional formula, Nd 0.67 A 0.33 MnO 3 (A = Ca, Sr, Pb and Ba) were prepared by Polyvinly Alcohol (PVA) gel route. After characterizing the samples by X-ray diffraction studies and by measuring electrical, magnetic transition temperatures, a systematic investigation of magnetization and magnetoresistance measurements both as a function of magnetic field and temperature was undertaken. The variation of electrical and magnetic transition temperatures is explained on the basis of size variance parameter. It has been concluded from the M–H plots that NCMO, NPMO and NBMO samples are exhibiting narrow hystersis loops indicating soft ferromagnetic nature, while the NSMO is found to exhibit double hystersis loop indicating the presence of metamagnetic transition. It is also observed that among the four samples, Nd 0.67 Ca 0.33 MnO 3 is found to exhibit the highest magnetoresistance (MR) of 91% over a broad temperature region. |
Full Text from ScienceDirect