Spin-orbit controlled quantum capacitance of a polar heterostructure

Steffen, Kevin; Loder, Florian; Kopp, Thilo

doi:10.1103/physrevb.91.075415

Cited by 7 publications

(9 citation statements)

References 35 publications

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“…The Rashba-like effects due to the combined atomic spin-orbit coupling and the orbitally driven inversion-symmetry term can be influenced by the application of an external electric field (e.g., via gating) in a dual way. On one hand, the gating directly modifies the filling concentration and, on the other, it can affect the deformation of the orbital lobes by changing the amplitude of the polar distortion 85,86 . In this paper, we set t 1 = t 2 ≡ t as a unit of energy for convenience and clarity of presentation.…”

Section: Model and Symmetry Classification Of Superconducting Phamentioning

confidence: 99%

Interorbital topological superconductivity in spin-orbit coupled superconductors with inversion symmetry breaking

et al. 2018

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We study the superconducting state of multi-orbital spin-orbit coupled systems in the presence of an orbitally driven inversion asymmetry assuming that the inter-orbital attraction is the dominant pairing channel. Although the inversion symmetry is absent, we show that superconducting states that avoid mixing of spin-triplet and spin-singlet configurations are allowed, and remarkably, spintriplet states that are topologically nontrivial can be stabilized in a large portion of the phase diagram. The orbital-dependent spin-triplet pairing generally leads to topological superconductivity with point nodes that are protected by a nonvanishing winding number. We demonstrate that the disclosed topological phase can exhibit Lifshitz-type transitions upon different driving mechanisms and interactions, e.g., by tuning the strength of the atomic spin-orbit and inversion asymmetry couplings or by varying the doping and the amplitude of order parameter. Such distinctive signatures of the nodal phase manifest through an extraordinary reconstruction of the low-energy excitation spectra both in the bulk and at the edge of the superconductor.

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Section: Model and Symmetry Classification Of Superconducting Phamentioning

confidence: 99%

Interorbital topological superconductivity in spin-orbit coupled superconductors with inversion symmetry breaking

et al. 2018

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“…at z = 0 − . We made this simplifying choice, which turns out to be slightly less favorable to the occurrence of PS, to avoid the distinction between the case of oxygen vacancies (for which the countercharge would be uniformly distributed in the LXO) and the polarity catastrophe (in which the countercharges suitably distribute themselves in the polar planes of LXO in order to minimize the energy [39]). Having fixed the positive charges, we consider the electric field at z = 0 + (i.e., the slope of the confining potential) at the interface.…”

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confidence: 99%

Phase Separation from Electron Confinement at Oxide Interfaces

et al. 2016

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Oxide heterostructures are of great interest both for fundamental and applicative reasons. In particular the two-dimensional electron gas at the LaAlO3/SrTiO3 or LaTiO3/SrTiO3 interfaces displays many different physical properties and functionalities. However there are clear indications that the interface electronic state is strongly inhomogeneous and therefore it is crucially relevant to investigate possible intrinsic electronic mechanisms underlying this inhomogeneity. Here the electrostatic potential confining the electron gas at the interface is calculated self-consistently, finding that the electron confinement at the interface may induce phase separation, to avoid a thermodynamically unstable state with a negative compressibility. This provides a generic robust and intrinsic mechanism for the experimentally observed inhomogeneous character of these interfaces.PACS numbers: 73.43.Nq,73.21.Fg, The two-dimensional electron gas (2DEG) that forms at the interface of two insulating oxides, like LaAlO 3 /SrTiO 3 and LaTiO 3 /SrTiO 3 (hereafter generically referred to as LXO/STO) [1][2][3][4], exhibits a rich phenomenology, such as a gate-tunable metal-tosuperconductor transition [5][6][7][8], a magnetic-field-tuned quantum criticality [9], and inhomogeneous magnetic responses [10][11][12][13][14][15]. Tunneling [16,17] and SQUID magnetometry [18] provide clear evidence of an inhomogeneous interface on both micro-and nanoscopic scales. Transport measurements report further signs of inhomogeneity and a percolative metal-to-superconductor transition with a sizable fraction of the 2DEG never becoming superconducting down to the lowest accessible temperatures [19][20][21][22]. For both fundamental reasons and applicative purposes, like device design, it is crucial to identify possible intrinsic mechanisms that may render the 2DEG so strongly inhomogeneous via a phase separation (PS). This is precisely the focus of the present work.Here, we identify a very effective electron-driven mechanism leading to PS, based on the confinement of the 2DEG at the interface. From customary self-consistent calculations of the confining potential well in semiconductors, it is well known [23] that a finite lateral extension usually renders the 2DEG more compressible than its strictly 2D counterpart. This effect is much stronger in LXO/STO than in ordinary semiconductor interfaces, due to the huge dielectric constant of STO, allowing for much larger electron densities, with a strong amplification of the self-consistent adjustments of the confining potential. As a consequence, a non-rigid band structure arises, which varies with the local electron density: an increased electron density is accompanied by a corresponding increase of the positive countercharges (due to oxygen vacancies and/or polarity catastrophe [24][25][26][27][28][29]), from which the interfacial electrons are introduced and restoring the overall charge neutrality. For small-to-moderate increases of electron and countercharge densities the potential well deepens and the e...

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“…36 Moreover, ∆ if is supposed to be field dependent. 37 Finally, we introduce disorder into the Hamiltonian by Ĥimp , which represents potential scattering at dislocations that are at position r i ,…”

Section: A Model For Spin-orbit Coupling In Laalo3/srtio3 Heterostruc...mentioning

confidence: 99%

The mechanism of spin-orbit coupling in a 2D oxide interface

Seiler,

Zabaleta,

Wanke

et al. 2016

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Spin-orbit controlled quantum capacitance of a polar heterostructure

Cited by 7 publications

References 35 publications

Interorbital topological superconductivity in spin-orbit coupled superconductors with inversion symmetry breaking

Interorbital topological superconductivity in spin-orbit coupled superconductors with inversion symmetry breaking

Phase Separation from Electron Confinement at Oxide Interfaces

The mechanism of spin-orbit coupling in a 2D oxide interface

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