electrodes*

We report a study of tunneling electroresistance (TER) in epitaxial ferroelectric tunnel junctions (FTJs) composed of ferroelectric PbZr_0.2Ti_0.8O₃ (PZT) barriers and correlated oxide electrodes. Epitaxial heterostructures LaNiO₃ (LNO)/PZT/SrIrO₃, LNO/PZT/La_0.67Sr_0.33MnO₃, and LNO/PZT/LNO) are deposited on SrTiO₃ (001) substrates via off-axis RF magnetron sputtering, with atomically smooth surface and high crystallinity achieved. The heterostructures are fabricated into tunnel junction devices with cross-strip geometry via photolithography followed by Ar ion milling. Switching the polarization of PZT leads to nonvolatile, reversal modulation of the tunneling current. The maximum room temperature TER ratio is observed in the LNO (8 nm)/PZT (4 nm)/LNO (12 nm) device, reaching about 1,000%. We exploit the Brinkman model to fit the tunneling current and investigate the temperature and magnetic field dependences of TER. Our study provides information about the critical material parameters for designing all-oxide epitaxial FTJs.