Volume 79, Number 6, September 2007
Article Number 67002
Number of page(s) 6
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
Published online 09 August 2007
EPL, 79 (2007) 67002
DOI: 10.1209/0295-5075/79/67002

Low-temperature magnetotransport properties in granular ferromagnetic manganites

Soumik Mukhopadhyay and I. Das

ECMP Division, Saha Institute of Nuclear Physics - 1/AF, Bidhannagar, Kolkata 700 064, India

received 18 April 2007; accepted in final form 23 July 2007; published September 2007
published online 9 August 2007

The magnetotransport properties at low temperature in La0.67Sr0.33MnO3 nanoparticles, La0.67Sr0.33MnO3/Al2O3 nanocomposites and ferromagnetic-manganite thick films have been studied. All the samples exhibit low-temperature upturn in resistivity and enhanced low-field magnetoresistance of varying magnitude below the resistivity minima. The voltage dependence of conductance at low temperature for all the samples can be described by a universal scaling function $G=G_{0}\,{\rm exp}\,(V/V_{0})^{1/2}$, where the scaling parameter V0 is sensitive to the magnetic field. The observed magnetotransport properties are explained in a unified treatment incorporating both inter-grain tunneling conduction and thermal activation over the inter-grain potential barrier lowered by the electric field.

73.63.-b - Electronic transport in nanoscale materials and structures.
72.25.-b - Spin polarized transport.
75.47.Lx - Manganites.

© Europhysics Letters Association 2007