84 research outputs found
Spin-Hall Current and Nonlocal Transport in Ferromagnet-Free Multi-band models for Sr Ti O_3-Based Nanodevices in the presence of impurities
We compute the spin-Hall conductance in a multiband model describing the
two-dimensional electron gas formed at a LaAlO_3/SrTiO_3 interface in the
presence of a finite concentration of impurities. Combining linear response
theory with a systematic calculation of the impurity contributions to the
self-energy, as well as to the vertex corrections of the relevant diagrams, we
recover the full spin-Hall vs. sheet conductance dependence of LaAlO_3/SrTiO_3
as reported in [Nano Lett. 20, 395 (2020)], finding a very good agreement with
the experimental data below and above the Lifshitz transition. In particular,
we demonstrate that the multiband electronic structure leads to only a partial,
instead of a complete, screening of the spin-Hall conductance, which decreases
with increasing the carrier density. Our method can be generalized to other
two-dimensional systems characterized by a broken inversion
symmetry and multiband physics.Comment: 21 pages, 11 .eps figure
Quantization of Hall Resistance at the Metallic Interface between an Oxide Insulator and SrTiO
The two-dimensional metal forming at the interface between an oxide insulator
and SrTiO3 provides new opportunities for oxide electronics. However, the
quantum Hall effect, one of the most fascinating effects of electrons confined
in two dimensions, remains underexplored at these complex oxide
heterointerfaces. Here, we report the experimental observation of quantized
Hall resistance in a SrTiO3 heterointerface based on the modulation-doped
amorphous-LaAlO/SrTiO heterostructure, which exhibits both high
electron mobility exceeding 10000 cm/Vs and low carrier density on the
order of ~10 cm. Along with unambiguous Shubnikov-de Haas
oscillations, the spacing of the quantized Hall resistance suggests that the
interface is comprised of a single quantum well with ten parallel conducting
two-dimensional subbands. This provides new insight into the electronic
structure of conducting oxide interfaces and represents an important step
towards designing and understanding advanced oxide devices
Evidence of weak superconductivity at the room-temperature grown LaAlO<sub>3</sub>/SrTiO<sub>3</sub> interface
The two-dimensional electron gas at the crystalline LaAlO3/SrTiO3 (c-LAO/STO) interface has sparked large interest due to its exotic properties, including an intriguing gate-tunable superconducting phase. While there is growing evidence of pronounced spatial inhomogeneity in the conductivity at STO-based interfaces, the consequences for superconductivity remain largely unknown. We study interfaces based on amorphous LAO top layers grown at room temperature (a-LAO/STO) and demonstrate a superconducting phase similar to c-LAO/STO, however, with a gate-tunable critical temperature of 460 mK. The dependence of the superconducting critical current on temperature, magnetic field, and back-gate-controlled doping is found to be consistently described by a model of a random array of Josephson-coupled superconducting domains
Creation of high mobility two-dimensional electron gases via strain induced polarization at an otherwise nonpolar complex oxide interface
The discovery of two-dimensional electron gases (2DEGs) in SrTiO3-based
heterostructures provides new opportunities for nanoelectronics. Herein, we
create a new type of oxide 2DEG by the epitaxial-strain-induced polarization at
an otherwise nonpolar perovskite-type interface of CaZrO3/SrTiO3. Remarkably,
this heterointerface is atomically sharp, and exhibits a high electron mobility
exceeding 60,000 cm2V-1s-1 at low temperatures. The 2DEG carrier density
exhibits a critical dependence on the film thickness, in good agreement with
the polarization induced 2DEG scheme.Comment: 19 pages, 4 figs; Nano Letters,2015, published onlin
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