Resonant tunneling driven metal-insulator transition in double quantum-well structures of strongly correlated oxide

Abstract

The metal-insulator transition (MIT), a fascinating phenomenon occurring in some strongly correlated materials, is of central interest in modern condensed-matter physics. Controlling the MIT by external stimuli is a key technological goal for applications in future electronic devices. However, the standard control by means of the field effect, which works extremely well for semiconductor transistors, faces severe difficulties when applied to the MIT. Hence, a radically different approach is needed. Here, we report an MIT induced by resonant tunneling (RT) in double quantum well (QW) structures of strongly correlated oxides. In our structures, two layers of the strongly correlated conductive oxide SrVO3 (SVO) sandwich a barrier layer of the band insulator SrTiO3 (STO). The top QW is a marginal Mott-insulating SVO layer, while the bottom QW is a metallic SVO layer. Angle-resolved photoemission spectroscopy experiments reveal that the top QW layer becomes metallized when the thickness of the tunneling barrier layer is reduced. An analysis based on band structure calculations indicates that RT between the quantized states of the double QW induces the MIT. Our work opens avenues for realizing the Mott-transistor based on the wave-function engineering of strongly correlated electrons.

Heteroepitaxial control of Fermi liquid, Hund metal, and Mott insulator phases in the single-atomic-layer limit

“…The underlying 4-UC SRO conducting layer can supply electrons to the n-UC ultrathin layer, which prevents the charging effect during angle-resolved photoemission spectroscopy (ARPES) measurements. At the same time, the 10-UC insulating buffer layer electronically separates the conducting and ultrathin layers [14,30]. The key idea is that a variety of interface configurations can be achieved with the same epitaxial strain by using different buffer layers.…”