The problem of quantum transport in chaotic cavities with broken time-reversal symmetry is shown to be completely integrable in the universal limit. This observation is utilized to determine the cumulants and the distribution function of conductance for a cavity with ideal leads supporting an arbitrary number n of propagating modes. Expressed in terms of solutions to the fifth Painlevé transcendent and/or the Toda lattice equation, the conductance distribution is further analyzed in the large-n limit that reveals long exponential tails in the otherwise Gaussian curve.
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http://dx.doi.org/10.1103/PhysRevLett.101.176804 | DOI Listing |
Adv Mater
January 2025
Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB3 0FS, UK.
Thick metamorphic buffers are considered indispensable for III-V semiconductor heteroepitaxy on large lattice and thermal-expansion mismatched silicon substrates. However, III-nitride buffers in conventional GaN-on-Si high electron mobility transistors (HEMT) impose a substantial thermal resistance, deteriorating device efficiency and lifetime by throttling heat extraction. To circumvent this, a systematic methodology for the direct growth of GaN after the AlN nucleation layer on six-inch silicon substrates is demonstrated using metal-organic vapor phase epitaxy (MOVPE).
View Article and Find Full Text PDFAdv Mater
January 2025
National & Local Joint Engineering Research Center for High-efficiency Display and Lighting Technology, Key Lab for Special Functional Materials of Ministry of Education, School of Nanoscience and Materials Engineering, Henan University, Kaifeng, 475004, China.
The poor efficiency and stability of blue Quantum Dot Light-Emitting diodes (QLED) hinders the practical applications of QLEDs full-color displays. Excessive electron injection, insufficient hole injection, and abundant defects on the surface of quantum dots (QD) are the main issues limiting the performance of blue devices. Herein, an in situ treatment with bipolar small molecule polydentate ligand-guanidine chloride (GACl) is proposed to simultaneously suppress excessive electron injection, patch surface defects of QDs and enhance hole injection.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
National University of Singapore - Kent Ridge Campus: National University of Singapore, Department of Chemistry, Faculty of Science, 3 Science Drive 3, 117543, Singapore, SINGAPORE.
Figure-eight macrocycles represent a fascinating class of π-conjugated units characterized by unique aesthetics and non-contact molecular crossing at the center. Despite progress in synthesis over the past century, research into inorganic, organic, and polymeric figure-eight materials remains in its infancy. Here we report the first examples of figure-eight covalent organic frameworks by condensing figure-eight knots to create extended porous figure-eight π architectures.
View Article and Find Full Text PDFEnviron Toxicol Chem
January 2025
Environmental Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA.
The leakage and accumulation of plastic in the environment is a significant and growing problem with numerous detrimental impacts and has led to a push toward the design and development of more environmentally benign materials. To this end we have developed a quantum chemistry (QC) based model for predicting the mobility of polymer materials from molecular structure. Hydrophobicity is used as a surrogate for mobility given that hydrophobic interactions drive much of the partitioning of contaminants in and out of various environmentally relevant compartments.
View Article and Find Full Text PDFNature
January 2025
Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
Electrons in topological flat bands can form new topological states driven by correlation effects. The pentalayer rhombohedral graphene/hexagonal boron nitride (hBN) moiré superlattice was shown to host fractional quantum anomalous Hall effect (FQAHE) at approximately 400 mK (ref. ), triggering discussions around the underlying mechanism and role of moiré effects.
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