Ultrafast Modification of the Polarity at LaAlO$_3$/SrTiO$_3$ Interfaces

TL;DR

This paper demonstrates that the polarization at LaAlO$_3$/SrTiO$_3$ interfaces can be ultrafastly modified using optical methods, revealing dynamic control over interface properties within picoseconds.

Contribution

It introduces a novel method to optically modulate the polarization state at oxide interfaces on ultrafast timescales, expanding understanding of dynamic interface phenomena.

Findings

Polarization at the interface can be enhanced or attenuated within picoseconds.

Charge propagation effects explain the observed ultrafast polarization changes.

Transient polarization buildup is key to the modulation mechanism.

Abstract

Oxide growth with semiconductor-like accuracy has led to atomically precise thin films and interfaces that exhibit a plethora of phases and functionalities not found in the oxide bulk material. This yielded spectacular discoveries such as the conducting, magnetic or even superconducting LaAlO$_3$/SrTiO$_3$ interfaces separating two prototypical insulating perovskite materials. All these investigations, however, consider the static state at the interface, although studies on fast oxide interface dynamics would introduce a powerful degree of freedom to understanding the nature of the LaAlO$_3$/SrTiO$_3$ interface state. Here we show that the polarization state at the LaAlO$_3$/SrTiO$_3$ interface can be optically enhanced or attenuated within picoseconds. Our observations are explained by a model based on charge propagation effects in the interfacial vicinity and transient polarization buildup at the interface.