Response of the capacitance of a planar La0.67Ca0.33MnO3/SrTiO3/La0.67Ca0.33MnO3 heterostructure to an electric field

Manganite film electrodes were integrated with a spacer layer of strontium titanate to produce an epitaxial La(0.67)Ca(0.33)MnO(3)/(1000 nm)SrTiO(3)/La(0.67)Ca(0.33)MnO(3) (LCMO/STO/LCMO) heterostructure by laser ablation. At T = 300 K, the mechanical stresses in the STO layer relaxed to a considerable extent, while the LCMO electrodes were found to be under biaxial lateral tensile strain, with the lattice unit cell of the top electrode distorted considerably stronger (a (ayen)/a (aSyen) a parts per thousand 1.026) than that of the bottom electrode (a parts per thousand 1.008) (a (ayen) and a (aSyen) are the unit cell parameters in the substrate plane and along the normal to its surface, respectively). The reciprocal of the capacitance C of the plane-parallel LCMO/STO/LCMO film capacitors thus formed increased almost linearly with increasing temperature T in the range 50-250 K. At T < 100 K, the capacitance C decreased by approximately 50% in an electric field E = 40 kV/cm. After the electric field E was varied as 0 -> + 100 kV/cm -> 0, the capacitance C decreased by approximately 3% and the maximum in the C(E, T > 200 K) dependence shifted by approximately 9 kV/cm with respect to the point E = 0.