Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userTransport in strongly-coupled graphene-LaAlO3/SrTiO3 hybrid systems
197
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We report on the transport properties of hybrid devices obtained by depositing graphene on a LaAlO3/SrTiO3 oxide junction hosting a 4 nm-deep two-dimensional electron system. At low graphene-oxide inter-layer bias the two electron systems are electrically isolated, despite their small spatial separation, and very efficient reciprocal gating is shown. A pronounced rectifying behavior is observed for larger bias values and ascribed to the interplay between electrostatic depletion and tunneling across the LaAlO3 barrier. The relevance of these results in the context of strongly-coupled bilayer systems is discussed.
rate research
Read More
The oxide heterostructure LaAlO3/SrTiO3 supports a two-dimensional electron liquid with a variety of competing phases including magnetism, superconductivity and weak antilocalization due to Rashba spin-orbit coupling. Further confinement of this 2D electron liquid to the quasi-one-dimensional regime can provide insight into the underlying physics of this system and reveal new behavior. Here we describe magnetotransport experiments on narrow LaAlO3/SrTiO3 structures created by a conductive atomic force microscope lithography technique. Four-terminal local transport measurements on ~10-nm-wide Hall bar structures yield longitudinal resistances that are comparable to the resistance quantum h/e2 and independent of the channel length. Large nonlocal resistances (as large as 10^4 ohms) are observed in some but not all structures with separations between current and voltage that are large compared to the 2D mean-free path. The nonlocal transport is strongly suppressed by the onset of superconductivity below ~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.
We report transport measurements through graphene on SrTiO3 substrates as a function of magnetic field B, carrier density n, and temperature T. The large dielectric constant of SrTiO3 screens very effectively long-range electron-electron interactions and potential fluctuations, making Dirac electrons in graphene virtually non-interacting. The absence of interactions results in a unexpected behavior of the longitudinal resistance in the N=0 Landau level, and in a large suppression of the transport gap in nano-ribbons. The bulk transport properties of graphene at B=0T, on the contrary, are completely unaffected by the substrate dielectric constant.
Double-layer electronic systems enable the investigation of interlayer quasiparticle interactions and the discovery of intriguing interlayer correlated states. Here we report interlayer drag measurements between graphene and superconducting LaAlO3/SrTiO3 (LAO/STO) heterointerface separated by a natural insulating barrier of LAO (as thin as 2 nm). Applying a drive current (Idrive) in the graphene layer induces a negative drag voltage at the LAO/STO interface in the vicinity of the superconducting transition, which is attributed to the supercurrent drag effect, arising from the interlayer interactions involving the superconducting carriers. Benefiting from the high tunability of both layers and the ultra-small interlayer spacing, an extremely large interlayer current coupling ratio (r = |Idrag/Idrive|, Idrag: the equivalent drag current at LAO/STO interface) is eventually achieved, surpassing conventional systems consisting of normal metal and superconducting films by two orders of magnitude. More strikingly, this ratio is estimated to be up to 10^5 at the zero-temperature limit. The unique temperature- and carrier density/polarity-dependent behaviors suggest a brand-new microscopic interaction mechanism accounting for the observed giant supercurrent drag effect. Our study is anticipated to inspire further exploration of hybrid interlayer coupling via utilization of newly-emerging two-dimensional electronic systems, in particular those exhibiting long-range electronic and magnetic orders.
We report superconductivity in quasi-1D nanostructures created at the LaAlO3/SrTiO3 interface. Nanostructures having line widths w~10 nm are formed from the parent two-dimensional electron liquid using conductive atomic force microscope lithography. Nanowire cross-sections are small compared to the superconducting coherence length in LaAlO3/SrTiO3 (w<<xi~100 nm), placing them in the quasi-1D regime. Broad superconducting transitions with temperature and finite resistances in the superconducting state well below Tc~200 mK are observed. V-I curves show switching between the superconducting and normal states that are characteristic of superconducting nanowires. The four-terminal resistance in the superconducting state shows an unusual dependence on the current path, varying by as much as an order of magnitude.
We present transport measurements on a strongly coupled graphene quantum dot in a perpendicular magnetic field. The device consists of an etched single-layer graphene flake with two narrow constrictions separating a 140 nm diameter island from source and drain graphene contacts. Lateral graphene gates are used to electrostatically tune the device. Measurements of Coulomb resonances, including constriction resonances and Coulomb diamonds prove the functionality of the graphene quantum dot with a charging energy of around 4.5 meV. We show the evolution of Coulomb resonances as a function of perpendicular magnetic field, which provides indications of the formation of the graphene specific 0th Landau level. Finally, we demonstrate that the complex pattern superimposing the quantum dot energy spectra is due to the formation of additional localized states with increasing magnetic field.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
