A switchable two-dimensional electron gas based on ferroelectric Ca:SrTiO${}_3$

Abstract

Two-dimensional electron gases (2DEGs) can form at the surface of oxides and semiconductors or in carefully designed quantum wells and interfaces. Depending on the shape of the confining potential, 2DEGs may experience a finite electric field, which gives rise to relativistic effects such as the Rashba spin-orbit coupling. Although the amplitude of this electric field can be modulated by an external gate voltage, which in turn tunes the 2DEG carrier density, sheet resistance and other related properties, this modulation is volatile. Here, we report the design of a ''ferroelectric'' 2DEG whose transport properties can be electrostatically switched in a non-volatile way. We generate a 2DEG by depositing a thin Al layer onto a SrTiO${}_3$ single crystal in which 1 percent of Sr is substituted by Ca to make it ferroelectric. Signatures of the ferroelectric phase transition at 25 K are visible in the Raman response and in the temperature dependences of the carrier density and sheet resistance that shows a hysteretic dependence on electric field as a consequence of ferroelectricity. We suggest that this behavior may be extended to other oxide 2DEGs, leading to novel types of ferromagnet-free spintronic architectures.

References in corpus (19)

• Electric Field Control of the LaAlO${}_3$/SrTiO${}_3$ Interface Ground State
• Unveiling a two-dimensional electron gas with universal subbands at the surface of SrTiO3
• Highly efficient and tuneable spin-to-charge conversion through Rashba coupling at oxide interfaces
• A ferroelectric-like structural transition in a metal
• Mapping the Spatial Distribution of Charge Carriers in LaAlO3/SrTiO3 Heterostructures
• A polarity-induced defect mechanism for conductivity and magnetism at polar-nonpolar oxide interfaces
• Profiling the interface electron gas of LaAlO3/SrTiO3 heterostructures by hard X-ray photoelectron spectroscopy
• A ferroelectric quantum phase transition inside the superconducting dome of Sr${}_{1-x}$Ca${}_x$TiO${}_{3-\delta }$
• Quantum critical origin of the superconducting dome in SrTiO${}_3$
• `Ferroelectric' Metals Reexamined: Fundamental Mechanisms and Design Considerations for New Materials
• Universal Fabrication of Two-Dimensional Electron Systems in Functional Oxides
• Fermi surface of the most dilute superconductor
• Ferroelectric Instability under Screened Coulomb Interactions
• Nanoscale ferroelectric manipulation of magnetic flux quanta
• Prediction of a native ferroelectric metal
• Ferroelectric enhancement of superconductivity in compressively strained SrTiO${}_3$ films
• Strain and ferroelectric soft mode induced superconductivity in strontium titanate
• Tuning up or down the critical thickness in LaAlO3/SrTiO3 through in situ deposition of metal overlayers
• Ferroelectric order versus metallicity in Sr${}_{1-x}$Ca${}_x$TiO${}_{3-\delta }$ ($x=0.009$)

Cited by in corpus (14)

• Oxide spin-orbitronics: spin-charge interconversion and topological spin textures
• Polar Metals Taxonomy for Materials Classification and Discovery
• Metal/SrTiO${}_3$ two-dimensional electron gases for spin-to-charge conversion
• Quantum Confinement and Electronic Structure at the Surface of van der Waals Ferroelectric α-In${}_2$Se${}_3$
• Recent Advances in Unconventional Ferroelectrics and Multiferroics
• Non-volatile electric control of spin-orbit torques in an oxide two-dimensional electron gas
• Evolution of domain structure with electron doping in ferroelectric thin films
• Mechanism for Switchability in Electron-Doped Ferroelectric Interfaces
• Universally enhanced superconductivity and coexisting ferroelectricity at oxide interfaces
• Revival of Layered Ferroelectrics in Thin Films
• Influence of a Realistic Multiorbital Band Structure on Conducting Domain Walls in Perovskite Ferroelectrics
• Externally controlled and switchable 2D electron gas at the Rashba interface between ferroelectrics and heavy $d$ metals
• KTaO3(001) Preparation Methods in Vacuum: Effects on Surface Stoichiometry, Crystallography, and in-gap States
• Many-body description of two-dimensional van der Waals ferroelectric $\alpha -$In${}_2$Se${}_3$