Metal-insulator transition of the LaAlO<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow /><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>-SrTiO<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow /><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>interface electron system

Liao, Y. C.; Kopp, Thilo; Richter, Christoph; Rosch, Achim; Mannhart, J.

doi:10.1103/physrevb.83.075402

Cited by 47 publications

(60 citation statements)

References 28 publications

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“…3f), we see that these densities have a universal value n C = 1.68 ± 0.18×10 13 cm − 2 independent of disorder, pointing to an intrinsic origin. The observed critical density is therefore fundamentally different from the recently determined metal-insulator transition density 26 , both in its experimental signature (below the metalinsulator transition the I-V characteristics are non-ohmic, whereas we see ohmic behaviour throughout except at the lowest densities, which are much smaller than n C ), as well as in its underlying source: the metal-insulator transition density is non-universal 26 , being set by the extrinsic disorder, whereas the critical density that we observe is universal, pointing to an intrinsic source. We argue that the observed transition is a Lifshitz transition that occurs when the density exceeds a critical value at which new bands of a different symmetry are populated.…”

Section: An Underlying Universal Lifshitz Transitionmentioning

confidence: 56%

A universal critical density underlying the physics of electrons at the LaAlO3/SrTiO3 interface

et al. 2012

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The two-dimensional electron system at the interface between the insulating oxides LaAlo 3 and srTio 3 exhibits ferromagnetism, superconductivity and a range of unique magnetotransportproperties. An open experimental challenge is to identify, out of the multitudinous energy bands predicted to exist at the interface, the key ingredients underlying its emergent transport phenomena. Here we show, using magnetotransport measurements, that a universal Lifshitz transition between d orbitals of different symmetries lies at the core of the observed phenomena. We find that LaAlo 3 /srTio 3 systems generically switch from one-to two-carrier transport at a universal carrier density, which is independent of the LaAlo 3 thickness and electron mobility. Interestingly, the maximum superconducting critical temperature occurs also at the Lifshitz density, indicating a possible connection between the two phenomena. A simple band model, allowing for spin-orbit coupling at the atomic level, connects the observed transition to a variety of previously reported properties. our results demonstrate that the fascinating behaviour observed so far in these oxides follows from a small but fundamental set of bands.

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Section: An Underlying Universal Lifshitz Transitionmentioning

confidence: 56%

A universal critical density underlying the physics of electrons at the LaAlO3/SrTiO3 interface

et al. 2012

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“…These phenomena emerge from the conducting state of the 2DEL, above a sharp metal-insulator transition (MIT), at a critical LAO thickness of 3 unit cells [2]. The MIT itself is quite remarkable and exhibits a temperature and electric field dependence that is distinct from ordinary semiconductors [3]. The existence of a conducting interface has been explained by a ''polar catastrophe'' model [1] in which the 2DEL forms to help screen the polarization of the LAO layer.…”

Section: Introductionmentioning

confidence: 99%

Anomalous Transport in Sketched Nanostructures at theLaAlO3/SrTiO3Interface

et al. 2013

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The oxide heterostructure LaAlO 3 =SrTiO 3 supports a two-dimensional electron liquid with a variety of competing phases, including magnetism, superconductivity, and weak antilocalization because of Rashba spin-orbit coupling. Further confinement of this two-dimensional electron liquid to the quasi-onedimensional regime can provide insight into the underlying physics of this system and reveal new behavior. Here, we describe magnetotransport experiments on narrow LaAlO 3 =SrTiO 3 structures created by a conductive atomic force microscope lithography technique. Four-terminal local-transport measurements on Hall bar structures about 10 nm wide yield longitudinal resistances that are comparable to the resistance quantum h=e 2 and independent of the channel length. Large nonlocal resistances (as large as 10 4 ) are observed in some but not all structures with separations between current and voltage that are large compared to the two-dimensional mean-free path. The nonlocal transport is strongly suppressed by the onset of superconductivity below about 200 mK. The origin of these anomalous transport signatures is not understood, but may arise from coherent transport defined by strong spin-orbit coupling and/or magnetic interactions.

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“…1 The specific interest in STO was sparked by the observation of a two-dimensional electron gas (2DEG) at a LaTiO 3 /STO interface, 2 and by subsequent observations [3][4][5][6][7][8] that these 2DEGs exhibit ferromagnetism and superconductivity. The ability to tune LAO/STO interfaces through metal-insulator and superconductor-insulator transitions by application of a gate voltage [9][10][11][12] has raised questions about the role of quantum criticality 13 and the origins of superconductivity at low electron density.…”

Section: Introductionmentioning

confidence: 99%

Temperature-dependent band structure ofSrTiO3interfaces

Raslan¹,

Lafleur²,

Atkinson³

2017

Phys. Rev. B

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We build a theoretical model for the electronic properties of the two-dimensional (2D) electron gas that forms at the interface between insulating SrTiO3 and a number of polar cap layers, including LaTiO3, LaAlO3, and GdTiO3. The model treats conduction electrons within a tight-binding approximation, and the dielectric polarization via a Landau-Devonshire free energy that incorporates strontium titanate's strongly nonlinear, nonlocal, and temperature-dependent dielectric response. The self-consistent band structure comprises a mix of quantum 2D states that are tightly bound to the interface, and quasi-three-dimensional (3D) states that extend hundreds of unit cells into the SrTiO3 substrate. We find that there is a substantial shift of electrons away from the interface into the 3D tails as temperature is lowered from 300 K to 10 K. This shift is least important at high electron densities (∼ 10 14 cm −2 ), but becomes substantial at low densities; for example, the total electron density within 4 nm of the interface changes by a factor of two for 2D electron densities ∼ 10 13 cm −2 . We speculate that the quasi-3D tails form the low-density high-mobility component of the interfacial electron gas that is widely inferred from magnetoresistance measurements.

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Metal-insulator transition of the LaAlO3-SrTiO3interface electron system

Cited by 47 publications

References 28 publications

A universal critical density underlying the physics of electrons at the LaAlO3/SrTiO3 interface

A universal critical density underlying the physics of electrons at the LaAlO3/SrTiO3 interface

Anomalous Transport in Sketched Nanostructures at theLaAlO3/SrTiO3Interface

Temperature-dependent band structure ofSrTiO3interfaces

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