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

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. 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. The metal-insulator transition is typically controlled by carrier accumulation or chemical doping. Here, the authors realize an alternative method based on resonant tunnelling in a double quantum well structure of strongly correlated oxides, which offers practical advantages over conventional methods.

Automated summary

In this study, the authors report on a metal-insulator transition induced by resonant tunnelling in a double quantum well structure of strongly correlated oxides, where reducing the thickness of the tunneling barrier layer leads to metallization of the top quantum well layer. This work opens up possibilities for Mott-transistor based on wave-function engineering of strongly correlated electrons.