Unabridged phase diagram for single-phased FeSexTe1-x thin films

A complete phase diagram and its corresponding physical properties are essential prerequisites to understand the underlying mechanism of iron based superconductivity. For the structurally simplest 11 (FeSeTe) system, earlier attempts using bulk samples have not been able to do so due to the fabrication difficulties. Here, thin FeSexTe1-x films with the Se content covering the full range were fabricated by using pulsed laser deposition method. Crystal structure analysis shows that all films retain the tetragonal structure in room temperature. Significantly, the highest superconducting transition temperature (TC = 20 K) occurs in the newly discovered domain, 0.6 - 0.8. The single-phased superconducting dome for the full Se doping range is the first of its kind in iron chalcogenide superconductors. Our results present a new avenue to explore novel physics as well as to optimize superconductors

Identification and modulation of electronic band structures of single-phase B-(AlxGa1-x)2O3 alloys grown by laser molecular beam epitaxy

Understanding the band structure evolution of (AlxGa1x)2O3 alloys is of fundamental importance for developing Ga2O3-based power electronic devices and vacuum ultraviolet super-radiation hard detectors. Here, we report on the bandgap engineering of b-(AlxGa1x)2O3 thin films and the identification of compositionally dependent electronic band structures by a combination of absorption spectra analyses and density functional theory calculations. Single-monoclinic b-phase (AlxGa1x)2O3 (0 x 0.54) films with a preferred (201) orientation were grown by laser molecular beam epitaxy with tunable bandgap ranging from 4.5 to 5.5 eV. The excellent fitting of absorption spectra by the relation of (ah) 1/2 / (h-E) unambiguously identifies that b-(AlxGa1x)2O3 alloys are indirect bandgap semiconductors. Theoretical calculations predict that the indirect nature of b-(AlxGa1x)2O3 becomes more pronounced with increased Al composition due to the increased eigenvalue energy gap between M and U points in the valence band. The experimentally determined indirect bandgap exhibits almost a linear relationship with Al composition, which is consistent with the theoretical calculation and indicates a small bowing effect and a good miscibility. The identification and modulation of (AlxGa1x)2O3 band structures allows rational design of ultra-wide bandgap oxide heterostructures for the applications in power electronics and solar-blind or X-ray detection.This research was supported by the National Key Research and Development Project (Grant No. 2017YFB0403003), the National Natural Science Foundation of China (Grant Nos. 61774081, 61322403, and 11227904), the Natural Science Foundation of Jiangsu Province (Grant Nos. BK20130013 and BK20161401), the Six Talent Peaks Project in Jiangsu Province (2014XXRJ001), the Fundamental Research Funds for the Central Universities (021014380093 and 021014380085) and the Australian Research Council. The computational part of this research was undertaken with the assistance of resources from the National Computational Infrastructure (NCI), which is supported by the Australian Government under the NCRIS program

The Ninth Visual Object Tracking VOT2021 Challenge Results

acceptedVersionPeer reviewe

DFT investigation of the geometrical and electronic structures of C

Geometrical and electronic structures of C35X fullerenes with $\rm X = B$, N and Si as substitutional dopants have been studied. Three non-equivalent sites in the D$_{6h}$ structure of C36 have been considered for the substitution. We have found that the dopant has a strong tendency to substitute at sites where the carbon atom contributes significantly to the frontier orbitals of C36 and has the weakest interaction with its nearest-neighbor atoms. The relative stability of C35Si and C35B (C35N) has been investigated and high chemical reactivity of C35Si has been predicted

Performance modulation of a-MnO2 nanowires by crystal facet engineering

Modulation of material physical and chemical properties through selective surface engineering is currently one of the most active research fields, aimed at optimizing functional performance for applications. The activity of exposed crystal planes determines the catalytic, sensory, photocatalytic, and electrochemical behavior of a material. In the research on nanomagnets, it opens up new perspectives in the fields of nanoelectronics, spintronics, and quantum computation. Herein, we demonstrate controllable magnetic modulation of α-MnO 2 nanowires, which displayed surface ferromagnetism or antiferromagnetism, depending on the exposed plane. First-principles density functional theory calculations confirm that both Mn- and O-terminated α-MnO2(1 1 0) surfaces exhibit ferromagnetic ordering. The investigation of surface-controlled magnetic particles will lead to significant progress in our fundamental understanding of functional aspects of magnetism on the nanoscale, facilitating rational design of nanomagnets. Moreover, we approved that the facet engineering pave the way on designing semiconductors possessing unique properties for novel energy applications, owing to that the bandgap and the electronic transport of the semiconductor can be tailored via exposed surface modulations

Effects of Linewidth Broadening Method on Recoil of Sodium Laser Guide Star

The linewidth broadening of the circular-polarized continuous wave laser mitigates the recoil effects of the sodium laser guide star very well. By choice of the optimal laser linewidth, the relations between the laser intensity and average spontaneous emission rates are obtained. The numerically simulated results show that the 1–100 MHz linewidth broadening effectively weakens recoil and enhances the average spontaneous emission rates. For laser powers from 10 W to 60 W, considering the intensity distribution with random at the mesospheric sodium layer, when the laser linewidth is broadened to be 1–100 MHz from 0 MHz, increments of the return photons go up to 110% from 50% and do not have an effect on the spot sizes of the sodium laser guide star. Several cases have proven that the linewidth broadening method is correct. Further calculations show that the linewidth broadening method similarly applies to the case of the multi-mode laser. Furthermore, the linewidth broadening of re-pumping should be taken into account