66 research outputs found
Charge writing at the LaAlO3/SrTiO3 surface
Biased conducting-tip atomic force microscopy (AFM) has been shown to write
and erase nanoscale metallic lines at the LaAlO3/SrTiO3 interface. Using
various AFM modes, we show the mechanism of conductivity switching is the
writing of surface charge. These charges are stably deposited on a wide range
of LaAlO3 thicknesses, including bulk crystals. A strong asymmetry with writing
polarity was found for 1 and 2 unit cells of LaAlO3, providing experimental
evidence for a theoretically predicted built-in potential.Comment: 12 pages, 4 figures, plus supplementary information, submitted to
Nano Letter
Superconductivity in epitaxially grown LaVO3/KTaO3(111) heterostructures
Complex oxide heterointerfaces can host a rich of emergent phenomena, and
epitaxial growth is usually at the heart of forming these interfaces. Recently,
a strong crystalline-orientation-dependent two-dimensional superconductivity
was discovered at interfaces between KTaO3 single-crystal substrates and films
of other oxides. Unexpectedly, rare of these oxide films was epitaxially grown.
Here, we report the existence of superconductivity in epitaxially grown
LaVO3/KTaO3(111) heterostructures, with a superconducting transition
temperature of ~0.5 K. Meanwhile, no superconductivity was detected in the
(001)- and (110)-orientated LaVO3/KTaO3 heterostructures down to 50 mK.
Moreover, we find that for the LaVO3/KTaO3(111) interfaces to be conducting, an
oxygen-deficient growth environment and a minimum LaVO3 thickness of ~0.8 nm (~
2 unit cells) are needed.Comment: 5 figures, plus 6 supplementary figure
Adversarial consistency for single domain generalization in medical image segmentation
7R01HL141813-06 - NIH/National Heart, Lung, and Blood Institute; NIH/National Institutes of HealthFirst author draf
Semi-Implicit Denoising Diffusion Models (SIDDMs)
Despite the proliferation of generative models, achieving fast sampling
during inference without compromising sample diversity and quality remains
challenging. Existing models such as Denoising Diffusion Probabilistic Models
(DDPM) deliver high-quality, diverse samples but are slowed by an inherently
high number of iterative steps. The Denoising Diffusion Generative Adversarial
Networks (DDGAN) attempted to circumvent this limitation by integrating a GAN
model for larger jumps in the diffusion process. However, DDGAN encountered
scalability limitations when applied to large datasets. To address these
limitations, we introduce a novel approach that tackles the problem by matching
implicit and explicit factors. More specifically, our approach involves
utilizing an implicit model to match the marginal distributions of noisy data
and the explicit conditional distribution of the forward diffusion. This
combination allows us to effectively match the joint denoising distributions.
Unlike DDPM but similar to DDGAN, we do not enforce a parametric distribution
for the reverse step, enabling us to take large steps during inference. Similar
to the DDPM but unlike DDGAN, we take advantage of the exact form of the
diffusion process. We demonstrate that our proposed method obtains comparable
generative performance to diffusion-based models and vastly superior results to
models with a small number of sampling steps
Imaging and tuning polarity at SrTiO3 domain walls.
Electrostatic fields tune the ground state of interfaces between complex oxide materials. Electronic properties, such as conductivity and superconductivity, can be tuned and then used to create and control circuit elements and gate-defined devices. Here we show that naturally occurring twin boundaries, with properties that are different from their surrounding bulk, can tune the LaAlO3/SrTiO3 interface 2DEG at the nanoscale. In particular, SrTiO3 domain boundaries have the unusual distinction of remaining highly mobile down to low temperatures, and were recently suggested to be polar. Here we apply localized pressure to an individual SrTiO3 twin boundary and detect a change in LaAlO3/SrTiO3 interface current distribution. Our data directly confirm the existence of polarity at the twin boundaries, and demonstrate that they can serve as effective tunable gates. As the location of SrTiO3 domain walls can be controlled using external field stimuli, our findings suggest a novel approach to manipulate SrTiO3-based devices on the nanoscale
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