Low-temperature magnetotransport properties in granular ferromagnetic manganitesSoumik 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 , 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