Paranjape, Mandar and Mitra, J and Raychaudhuri, AK and Todd, NK and Mathur, ND and Blamire, MG (2003) Nonlinear electrical transport through artificial grain-boundary junctions in La0.7Ca0.3MnO3 epitaxial thin films. In: Physical Review B (Condensed Matter and Materials Physics -1(II)), 68 . 144409-1-8.
We report investigation of non-linear electronic transport through artificial grain-boundary junctions made on epitaxial films of La0.7Ca0.3MnO3 on bicrystal SrTiO3 substrates. The experiments carried out over the temperature range 4.2 K–300 K in magnetic field up to 3 T allow us to identify some of the conduction mechanisms that may give rise to nonlinear transport in these grain boundary junctions. The nonlinear transport is associated with multistep inelastic processes in the grain-boundary region, which is moderately affected by the applied magnetic field. However the primary effect of the magnetic field is to enhance the zero-bias conductance [G0 = (dI/dV)V = 0]. The dominant voltage dependent contribution to the dynamic conductance (G = dI/dV) comes from a term of the type V4/3 at lower temperatures. Other voltage dependent contributions to G, which are of higher order in V, appear only for T>75 K. In addition we found a contribution to G arising from a V0.5 term, which is likely to arise from the disordered region around the grain boundary (GB). The magnetoresistance in the GB depends on the bias used and it decreases at higher bias. The bias dependence is found to be reduced as temperature is increased. We discuss the physical origins of the various contributions to the nonlinear conduction.
|Item Type:||Journal Article|
|Additional Information:||Copyright for this article belongs to American Physical Society (APS)|
|Department/Centre:||Division of Physical & Mathematical Sciences > Physics|
|Date Deposited:||25 Aug 2004|
|Last Modified:||19 Sep 2010 04:14|
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