Competition of electronic correlation and reconstruction in La1-xSrxTiO3/SrTiO3 heterostructures

TL;DR

This study investigates how electronic correlation and structural reconstruction compete in La1-xSrxTiO3/SrTiO3 heterostructures, revealing a critical thickness for metal-insulator transition influenced by doping, strain, and polarity.

Contribution

It demonstrates the interplay between electronic reconstruction and correlation in controlling phase transitions in heterostructures, highlighting the dependence on doping and strain.

Findings

Critical thickness for MIT varies with Sr doping.

V-shaped dependence of critical thickness on doping.

Coexistence of 2D and 3D carriers at transition.

Abstract

Electronic correlation and reconstruction are two important factors that play a critical role in shaping the magnetic and electronic properties of correlated low-dimensional systems. Here, we report a competition between the electronic correlation and structural reconstruction in La1-xSrxTiO3/SrTiO3 heterostructures by modulating material polarity and interfacial strain, respectively. The heterostructures exhibit a critical thickness (tc) at which a metal-to-insulator transition (MIT) abruptly occurs at certain thickness, accompanied by the coexistence of two- and three-dimensional (2D and 3D) carriers. Intriguingly, the tc exhibits a V-shaped dependence on the doping concentration of Sr, with the smallest tc value at x = 0.5. We attribute this V-shaped dependence to the competition between the electronic reconstruction (modulated by the polarity) and the electronic correlation (modulated by strain), which are borne out by the experimental results, including strain-dependent electronic properties and the evolution of 2D and 3D carriers. Our findings underscore the significance of the interplay between electronic reconstruction and correlation in the realization and utilization of emergent electronic functionalities in low-dimensional correlated systems.