Microstructure and dielectric relaxor properties for Ba₀.₅Sr₀. ₅TiO₃/La₀.₆₇Sr₀.₃₃MnO₃heterostructure

Abstract

Ferroelectric and magnetoresistance heterostructure (Ba,Sr)TiO₃/ (La,Sr)MnO₃(BST/LSMO) heterostructure is deposited epitaxially on SrTiO₃(001) substrate by pulse laser deposition. The phase structures of the BST/LSMO heterostructure are characterized by x-ray diffraction. Cross-sectional transmission electron microscope shows a substantial interdiffusision between BST and LSMO layers. The dielectric properties and conductivity of BST/LSMO heterostructure is measured as a function of temperature, frequency, and electric field. The dielectric constant dependence on electric field, ε vs E, exhibits a strong nonlinear behavior in the temperature from 20 to 300 K, while ε [sub(E=0)] vs T relation shows a dielectric relaxor characteristic. Furthermore, the dielectric constant (E=0 kV/cm) and the dielectric tunability (E=200 kV/cm) are found to be similar temperature dependencies. Last, in the temperature regime where a semiconduction-type conduction became dominate, the activation thermal energy of BST/LSMO heterostructure is estimated to be 0.67 and 0.73 eV at 1 kHz and 1 MHz, respectively.