Nonvolatile Ferroelectric Manipulation of Electronic Structure at LAO/STO Heterointerface

Hetero-interfaces between different oxide insulators have attracted a lot of interests. One of the most important system is the 2D electron gas at LaAlO$_{3}$(LAO) and SrTiO$_{3}$ (STO), which had been reported to possess metallic conduction and superconductivity. In this study, the top-patterned Pb(Zr$_{0.2}$Ti$_{0.8})$O$_{3}$ ferroelectric layer epitaxially grown on LAO/STO was proposed as a nonvolatile electronic modulation, and the interface band deformation was investigated using photoelectron spectroscopy (PES). Result showed different thickness and polarization state of top PZT significantly affected the band structure and its corresponding valence band offset at the LAO/STO hetero-interface. The transport data indicated that the as-grown PZT would deplete the conducting interface of LAO/STO, while switching the polarization of PZT would enhance the interface conduction.