313 research outputs found
Anomalous Hall effect at half filling in twisted bilayer graphene
Magic-angle twisted bilayer graphene (tBLG) has been studied extensively
owing to its wealth of symmetry-broken phases, correlated Chern insulators,
orbital magnetism, and superconductivity. In particular, the anomalous Hall
effect (AHE) has been observed at odd integer filling factors ( and )
in a small number of tBLG devices, indicating the emergence of a zero-field
orbital magnetic state with spontaneously broken time-reversal symmetry.
However, the AHE is typically not anticipated at half filling () owing
to competing intervalley coherent states, as well as spin-polarized and valley
Hall states that are favored by an intervalley Hund's coupling. Here, we
present measurements of two tBLG devices with twist angles slightly away from
the magic angle (0.96 and 1.20), in which we report the
surprising observation of the AHE at and , respectively. These
findings imply that a valley-polarized phase can become the ground state at
half filling in tBLG rotated slightly away from the magic angle. Our results
reveal the emergence of an unexpected ground state in the
intermediately-coupled regime (, where is the strength of
Coulomb repulsion and is the bandwidth), in between the strongly-correlated
insulator and weakly-correlated metal, highlighting the need to develop a more
complete understanding of tBLG away from the strongly-coupled limit.Comment: 13 pages, 10 figure
Advances of deep learning in electrical impedance tomography image reconstruction
Electrical impedance tomography (EIT) has been widely used in biomedical research because of its advantages of real-time imaging and nature of being non-invasive and radiation-free. Additionally, it can reconstruct the distribution or changes in electrical properties in the sensing area. Recently, with the significant advancements in the use of deep learning in intelligent medical imaging, EIT image reconstruction based on deep learning has received considerable attention. This study introduces the basic principles of EIT and summarizes the application progress of deep learning in EIT image reconstruction with regards to three aspects: a single network reconstruction, deep learning combined with traditional algorithm reconstruction, and multiple network hybrid reconstruction. In future, optimizing the datasets may be the main challenge in applying deep learning for EIT image reconstruction. Adopting a better network structure, focusing on the joint reconstruction of EIT and traditional algorithms, and using multimodal deep learning-based EIT may be the solution to existing problems. In general, deep learning offers a fresh approach for improving the performance of EIT image reconstruction and could be the foundation for building an intelligent integrated EIT diagnostic system in the future
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