Ferroelectric Exchange Bias Affects Interfacial Electronic States

TL;DR

This study investigates how ferroelectric exchange bias influences interfacial electronic states at the LaAlO3/SrTiO3 interface, revealing intrinsic biases that can be used to control ferroelectric properties and develop memory devices.

Contribution

It demonstrates the impact of ferroelectric exchange bias on interfacial electronic states and proposes using intrinsic bias for controlling ferroelectric and superconducting properties.

Findings

Anomalous low-temperature resistivity behavior observed.

Intrinsic bias from polar LaAlO3 influences current flow.

Hysteretic gate voltage effects suggest potential for memory devices.

Abstract

In polar oxide interfaces phenomena such as conductivity, superconductivity, magnetism, one-dimensional conductivity and Quantum Hall states can emerge at the polar discontinuity. Combining controllable ferroelectricity at such interfaces can affect the superconducting properties and shed light on the mutual effects between the polar oxide and the ferroelectric oxide. Here we study the interface between the polar oxide LaAlO3 and the ferroelectric Ca-doped SrTiO3 by means of electrical transport combined with local imaging of the current flow with the use of scanning Superconducting Quantum Interference Device (SQUID). Anomalous behavior of the interface resistivity is observed at low temperatures. The scanning SQUID maps of the current flow suggest that this behavior originates from an intrinsic bias induced by the polar LaAlO3 layer. Our data imply that the intrinsic bias combined with ferroelectricity constrain the possible structural domain tiling near the interface. We recommend the use of this intrinsic bias as a method of controlling and tuning the initial state of ferroelectric materials by design of the polar structure. The hysteretic dependence of the normal and the superconducting state properties on gate voltage can be utilized in multifaceted controllable memory devices.