Electric, magnetic, and thermo-electric properties of Cr doped La0.8Ca0.2Mn1−xCrxMnO3 manganites. (July 2016)

• Record Type: Journal Article
• Authors: Manjunatha, S.O.; Rao, Ashok; Babu, P.D.; Chand, Tara; Okram, G.S.
• Is Part Of: Solid state communications. Volume 239(2016)
• Page Start: 37
• Page End: 43
• Publication Date: 2016-07
• Subjects: Solid state chemistry -- Periodicals; Solid state physics -- Periodicals; Chimie de l'état solide -- Périodiques; Physique de l'état solide -- Périodiques; 530.41
• DOI: 10.1016/j.ssc.2016.04.012
• Languages: English
• ISSNs: 0038-1098

Abstract

Abstract: A detailed study of the structural, magnetic, magneto-transport and thermoelectric properties of polycrystalline La0.8 Ca0.2 Mn1− x Cr x MnO3 (0< x <0.07) compounds is presented in the present communication. XRD studies confirm that the samples are pure and single phased. We have observed from electrical and magnetic studies that all the samples are exhibiting metal–insulator transition temperature, T MI and ferromagnetic–paramagnetic ( FM–PM ) transition temperature, T C . With increasing Cr-content, both T MI and T C are observed to decrease. The electrical resistivity data is analyzed using different theoretical models at various regions viz., metallic, insulating and percolation region. Analysis in the metallic region ( T < T MI ) suggests that the electron–electron scattering in predominant in the region whereas the insulating region ( T > T MI ) is well described using SPH model. However, the resistivity data in the whole temperature range is analyzed using a phenomenological model based on phase segregation of ferromagnetic metallic and paramagnetic insulating regions. Thermoelectric power, S measurements were performed to understand the conduction mechanism and to ascertain the types of charge carrier responsible for conduction. It is observed that pristine as well as Cr-doped compounds show positive value of S which demonstrates that the charge carriers are holes. Highlights: Pristine and Cr-doped samples show metal–insulator transition. TMI and TC both decrease with Cr-content. Magnetic data shows that MZFC and MFC bifurcate below Curie temperature. High temperature thermoelectric power data follows small polaron hopping model.