Electron trapping and detrapping in an oxide two-dimensional electron gas: The role of ferroelastic twin walls

Abstract

The choice of electrostatic gating over the conventional chemical doping for phase engineering of quantum materials is attributed to the fact that the former can reversibly tune the carrier density without affecting the system's level of disorder. However, this proposition seems to break down in field-effect transistors involving SrTiO${}_3$ (STO) based two-dimensional electron gases. Such peculiar behavior is associated with the electron trapping under an external electric field. However, the microscopic nature of trapping centers remains an open question. In this paper, we investigate electric field-induced charge trapping/detrapping phenomena at the conducting interface between band insulators $\gamma$-Al${}_2$O${}_3$ and STO. Our transport measurements reveal that the charge trapping under +ve back gate voltage ($V_g$) above the tetragonal to cubic structural transition temperature ($T_c$) of STO is contributed by the electric field-assisted thermal escape of electrons from the quantum well, and the clustering of oxygen vacancies (OVs) as well. We observe an additional source of trapping below the $T_c$, which arises from the trapping of free carriers at the ferroelastic twin walls of STO. Application of -ve $V_g$ results in a charge detrapping, which vanishes above $T_c$ also. This feature demonstrates the crucial role of structural domain walls in the electrical transport properties of STO based heterostructures. The number of trapped (detrapped) charges at (from) the twin wall is controlled by the net polarity of the wall and is completely reversible with the sweep of $V_g$.

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References in corpus (19)

• Magnetic effects at the interface between nonmagnetic oxides
• Electric Field Control of the LaAlO${}_3$/SrTiO${}_3$ Interface Ground State
• Tunable Rashba spin-orbit interaction at oxide interfaces
• Strain gradient induced polarization in SrTiO3 single crystals
• Electric Field-Tuned Topological Phase Transition in Ultra-Thin Na3Bi - Towards a Topological Transistor
• Locally enhanced conductivity due to the tetragonal domain structure in LaAlO${}_3$/SrTiO${}_3$ heterointerfaces
• Quasiparticle dynamics and spin-orbital texture of the SrTiO3 two-dimensional electron gas
• Local Electrostatic Imaging of Striped Domain Order in LaAlO3/SrTiO3
• Imaging and tuning polarity at SrTiO3 domain walls
• Visible light enhanced field effect at LaAlO3/SrTiO3 interface
• Macroscopic Polarization from Antiferrodistortive Cycloids in Ferroelastic SrTiO${}_3$
• Pressure on charged domain walls and additional imprint mechanism in ferroelectrics
• Anomalous orbital structure in a spinel-perovskite interface $\gamma$-Al${}_2$O${}_3$/SrTiO${}_3$
• New insights into the electron trapping mechanism in LaAlO_3 / SrTiO3 heterostructures
• Microscopic origin of the mobility enhancement at a spinel/perovskite oxide heterointerface revealed by photoemission spectroscopy
• Magneto-transport study of top- and back-gated LaAlO${}_3$/SrTiO${}_3$ heterostructures
• Thermally activated recovery of electrical conductivity in LaAlO3/SrTiO3
• Oxygen Vacancy-Induced Topological Hall effect in a Nonmagnetic Band Insulator
• Electrostatic tuning of magnetism at the conducting (111) (La${}_{0.3}$Sr${}_{0.7}$)(Al${}_{0.65}$Ta${}_{0.35}$)/SrTiO${}_3$ interface

Cited by in corpus (7)

• Non-volatile electric control of spin-orbit torques in an oxide two-dimensional electron gas
• Flux-flow instability across Berezinskii Kosterlitz Thouless phase transition in KTaO${}_3$ (111) based superconductor
• Non-collinear and strongly asymmetric polar moments at back-gated SrTiO3 interfaces
• Domain wall nature of sketched LaAlO3/SrTiO3 nanowires
• Beyond being free: glassy dynamics of SrTiO${}_3$-based two-dimensional electron gas
• Universally enhanced superconductivity and coexisting ferroelectricity at oxide interfaces
• Site-selective polar compensation of Mott electrons in a double perovskite heterointerface