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Field-effect control of superconductivity and Rashba spin-orbit coupling in top-gated LaAlO3/SrTiO3 devices.

Hurand S, Jouan A, Feuillet-Palma C, Singh G, Biscaras J, Lesne E, Reyren N, Barthélémy A, Bibes M, Villegas JE, Ulysse C, Lafosse X, Pannetier-Lecoeur M, Caprara S, Grilli M, Lesueur J, Bergeal N - Sci Rep (2015)

Bottom Line: Here, we report on the realisation of a field-effect LaAlO3/SrTiO3 device, whose physical properties, including superconductivity and SOC, can be tuned over a wide range by a top-gate voltage.We derive a phase diagram, which emphasises a field-effect-induced superconductor-to-insulator quantum phase transition.Our results pave the way for the realisation of mesoscopic devices, where these two properties can be manipulated on a local scale by means of top-gates.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Physique et d'Etude des Matériaux -CNRS-ESPCI ParisTech-UPMC, PSL Research University, 10 Rue Vauquelin, 75005 Paris, France.

ABSTRACT
The recent development in the fabrication of artificial oxide heterostructures opens new avenues in the field of quantum materials by enabling the manipulation of the charge, spin and orbital degrees of freedom. In this context, the discovery of two-dimensional electron gases (2-DEGs) at LaAlO3/SrTiO3 interfaces, which exhibit both superconductivity and strong Rashba spin-orbit coupling (SOC), represents a major breakthrough. Here, we report on the realisation of a field-effect LaAlO3/SrTiO3 device, whose physical properties, including superconductivity and SOC, can be tuned over a wide range by a top-gate voltage. We derive a phase diagram, which emphasises a field-effect-induced superconductor-to-insulator quantum phase transition. Magneto-transport measurements show that the Rashba coupling constant increases linearly with the interfacial electric field. Our results pave the way for the realisation of mesoscopic devices, where these two properties can be manipulated on a local scale by means of top-gates.

No MeSH data available.


Related in: MedlinePlus

Spin-orbit splitting.Spin-orbit splitting as a function of VTG (bottom axis) and corresponding carrier density (top axis). Inset: Spin-orbit splitting as a function of temperature for selected VTG.
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f5: Spin-orbit splitting.Spin-orbit splitting as a function of VTG (bottom axis) and corresponding carrier density (top axis). Inset: Spin-orbit splitting as a function of temperature for selected VTG.

Mentions: The spin-orbit term (BSO) increases with top-gate voltage and, correspondingly, with the carrier density. The analysis of this dependence can shed light on the origin of the SOC at the LaAlO3/SrTiO3 interface. If we assume that the spin relaxation is dominated by the D’Yakonov-Perel mechanism, based on a Rashba spin-orbit interaction, 2630. We then obtain the relationship between the coupling constant and the spin-orbit effective field . Integrating the Maxwell-Gauss equation in the direction perpendicular to the interface gives the interfacial electric field where is the dielectric constant of Si3N4 at the interface and nt is the carrier density of non-mobile charges trapped in the SrTiO3 substrate. The coupling constant being proportional to Ez, it is therefore expected to vary with carrier density with the form α = an + b, which is well satisfied experimentally for a wide range of electrostatic doping (Fig. 5). This confirms experimentally that the D’Yakonov-Perel mechanism in the presence of Rashba spin-orbit interaction is dominant in these 2-DEGs.


Field-effect control of superconductivity and Rashba spin-orbit coupling in top-gated LaAlO3/SrTiO3 devices.

Hurand S, Jouan A, Feuillet-Palma C, Singh G, Biscaras J, Lesne E, Reyren N, Barthélémy A, Bibes M, Villegas JE, Ulysse C, Lafosse X, Pannetier-Lecoeur M, Caprara S, Grilli M, Lesueur J, Bergeal N - Sci Rep (2015)

Spin-orbit splitting.Spin-orbit splitting as a function of VTG (bottom axis) and corresponding carrier density (top axis). Inset: Spin-orbit splitting as a function of temperature for selected VTG.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4525493&req=5

f5: Spin-orbit splitting.Spin-orbit splitting as a function of VTG (bottom axis) and corresponding carrier density (top axis). Inset: Spin-orbit splitting as a function of temperature for selected VTG.
Mentions: The spin-orbit term (BSO) increases with top-gate voltage and, correspondingly, with the carrier density. The analysis of this dependence can shed light on the origin of the SOC at the LaAlO3/SrTiO3 interface. If we assume that the spin relaxation is dominated by the D’Yakonov-Perel mechanism, based on a Rashba spin-orbit interaction, 2630. We then obtain the relationship between the coupling constant and the spin-orbit effective field . Integrating the Maxwell-Gauss equation in the direction perpendicular to the interface gives the interfacial electric field where is the dielectric constant of Si3N4 at the interface and nt is the carrier density of non-mobile charges trapped in the SrTiO3 substrate. The coupling constant being proportional to Ez, it is therefore expected to vary with carrier density with the form α = an + b, which is well satisfied experimentally for a wide range of electrostatic doping (Fig. 5). This confirms experimentally that the D’Yakonov-Perel mechanism in the presence of Rashba spin-orbit interaction is dominant in these 2-DEGs.

Bottom Line: Here, we report on the realisation of a field-effect LaAlO3/SrTiO3 device, whose physical properties, including superconductivity and SOC, can be tuned over a wide range by a top-gate voltage.We derive a phase diagram, which emphasises a field-effect-induced superconductor-to-insulator quantum phase transition.Our results pave the way for the realisation of mesoscopic devices, where these two properties can be manipulated on a local scale by means of top-gates.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Physique et d'Etude des Matériaux -CNRS-ESPCI ParisTech-UPMC, PSL Research University, 10 Rue Vauquelin, 75005 Paris, France.

ABSTRACT
The recent development in the fabrication of artificial oxide heterostructures opens new avenues in the field of quantum materials by enabling the manipulation of the charge, spin and orbital degrees of freedom. In this context, the discovery of two-dimensional electron gases (2-DEGs) at LaAlO3/SrTiO3 interfaces, which exhibit both superconductivity and strong Rashba spin-orbit coupling (SOC), represents a major breakthrough. Here, we report on the realisation of a field-effect LaAlO3/SrTiO3 device, whose physical properties, including superconductivity and SOC, can be tuned over a wide range by a top-gate voltage. We derive a phase diagram, which emphasises a field-effect-induced superconductor-to-insulator quantum phase transition. Magneto-transport measurements show that the Rashba coupling constant increases linearly with the interfacial electric field. Our results pave the way for the realisation of mesoscopic devices, where these two properties can be manipulated on a local scale by means of top-gates.

No MeSH data available.


Related in: MedlinePlus