Tunnel conduction in epitaxial bilayers of ferromagnetic LaCoO₃/La₂/₃Sr₁/₃MnO₃ deposited by a chemical solution method.

Abstract

We report magnetic and electronic transport measurements across epitaxial bilayers of ferromagnetic insulator LaCoO3 and half-metallic ferromagnet La2/3Sr1/3MnO3 (LCO/LSMO: 3.5 nm/20 nm) fabricated by a chemical solution method. The I-V curves at room temperature and 4K measured with conducting atomic force microscopy (CAFM) on well-defined patterned areas exhibit the typical features of a tunneling process. The curves have been fitted to the Simmons model to determine the height (φ) and width (s) of the insulating LCO barrier. The results yield φ = 0.40 ± 0.05 eV (0.50 ± 0.01 eV) at room temperature (4K) and s = 3 nm, in good agreement with the structural analysis. Our results demonstrate that this chemical method is able to produce epitaxial heterostructures with the quality required for this type of fundamental studies and applications.