Article

Magnetoelectric behavior of sodium doped lanthanum manganites

Department of Physics, Osmania University, Hyderabad, Andhra Pradesh 500 007, India
Journal of Applied Physics (impact factor: 2.17). 08/2009; DOI:10.1063/1.3173285
Source: IEEE Xplore

ABSTRACT Nanocrystalline samples of sodium doped manganites with compositional formula La 1-x Na x Mn O 3 (0.025≤x≤0.25) were prepared by polyvinyl alcohol assisted precursor method. After characterizing the samples by x-ray diffraction and transmission electron microscopy a systematic investigation of electrical, magnetic, and thermopower properties has been undertaken. The resistivity data were analyzed using effective medium approximation. From the analysis it has been found that the metallic fraction is increasing up to x=0.10 and remains constant with further doping. A close examination of the resistivity data clearly indicates that the sodium doped samples are slowly transformed from colossal magnetoresistance behavior to charge ordering behavior. Thermoelectric power data at low temperatures were analyzed by considering the magnon drag concept, while the high temperature data were explained by small polaron conduction mechanism.

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Keywords

behavior
 
colossal magnetoresistance behavior
 
electrical
 
low temperatures
 
metallic fraction
 
Nanocrystalline samples
 
polyvinyl alcohol
 
precursor method
 
resistivity data
 
samples
 
sodium doped manganites
 
sodium doped samples
 
temperature data
 
transmission electron microscopy
 

Y Kalyana Lakshmi