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2D magnetic semiconductor CrSBr exhibits unique magneto-optical properties, yet its electronic structure and photophysical mechanisms remain unclear at high magnetic field and low temperature. Through comprehensive spectroscopic investigations, its charge-transfer band edge is identified at 500 nm. Below this band-edge, local excitonic magnetic polaronic states from Cr3+ ions out of FM aggregates in layer and bilayer could be seen due to phonon-spin-exciton coupling, in which magnetic polaronic PL1 emission occurs at 720 nm from single Cr3+ d-d transition, a dark-state pair exciton occurs at 850 nm in 10 K magnetic field, and double-peak PL2 emission at 920 nm out of Cr3+ FM trimer in monolayer is seen; besides, the magnetic bi-polaronic PL3 at 990 nm can be assigned to Cr3+ tetramers between FM adjacent layers. In magnetic field perpendicular to the layer, direct competition between PL1and dark-state excitons and PL2 and PL3 excitonic states persist in different temperatures. This study sheds light on the complicated magneto-exciton interactions in the multi-body effect of CrSBr, beneficial for quantum modulation in layered magnetic semiconductors.

Massive communication is one of key scenarios of 6G where two magnitude higher connection density would be required to serve diverse services. As a promising direction, unsourced multiple access has been proved to outperform significantly over orthogonal multiple access (OMA) or slotted-ALOHA in massive connections. In this paper we describe a design framework of unsourced sparse multiple access (USMA) that consists of two key modules: compressed sensing for preamble generation, and sparse interleaver division multiple access (SIDMA) for main packet transmission. Simulation results of general design of USMA show that the theoretical bound can be approached within 1~1.5 dB by using simple channel codes like convolutional. To illustrate the scalability of USMA, a customized design for ambient Internet of Things (A-IoT) is proposed, so that much less memory and computation are required. Simulations results of Rayleigh fading and realistic channel estimation show that USMA based A-IoT solution can deliver nearly 4 times capacity and 6 times efficiency for random access over traditional radio frequency identification (RFID) technology., Comment: 7 pages, 5 figures and 1 table

Amorphous polymer derived silicon oxycarbide (SiOC) is an attractive candidate for Lithium ion battery anodes, as an alternative to graphite, which is limited to a theoretical capacity of 372 mAh/g. However, SiOC tends to exhibit poor transport properties and cycling performance as a result of sparsely distributed carbon clusters and inefficient active sites. To overcome these limitations, we designed and fabricated a layered graphene SiOC heterostructure by solvent assisted infiltration of a polymeric precursor into a modified three dimensional graphene aerogel skeleton. The use of a high melting point solvent facilitated the precursors freeze drying, which following pyrolysis yielded SiOC as a layer supported on the surface of nitrogen doped reduced graphene oxide aerogels. The fabrication method employed here modifies the composition and microstructure of the SiOC phase. Among the studied materials, the highest levels of performance were obtained for a sample of moderate SiOC content, in which the graphene network constituted 19.8 wt % of the system. In these materials, a stable reversible charge capacity of 751 mAh/g was achieved at low charge rates. At high charge rates of 1480 mA/g, the capacity retention was ca. 95% (352 mAh/g) after 1000 consecutive cycles. At all rates, Coulombic efficiencies greater than 99% were maintained following the first cycle. Performance across all indicators was majorly improved in the graphene aerogel SiOC nanocomposites, compared with unsupported SiOC. The performance was attributed to mechanisms across multiple length scales. The presence of oxygen rich SiO4-xCx tetrahedral units and a continuous free carbon network within the SiOC provides sites for reversible lithiation, while high ionic and electronic transport is provided by the layered graphene SiOC heterostructure.

To develop high emissivity coatings on fibrous ceramic substrates with improved thermal resistance for reusable space systems, WSi2-MoSi2-Si-SiB6-borosilicate glass coatings were prepared on fibrous ZrO2 by slurry dipping and subsequent high temperature rapid sintering. A coating with 50 wt% WSi2 and 50 wt% MoSi2 presents optimal thermal stability with only 10.06 mg/cm2 mass loss and 4.0 % emissivity decrease in the wavelength regime of 1.27 to 1.73 microns after 50 h oxidation at 1773 K. The advantages of double phase metal silicide coatings combining WSi2 and MoSi2 include improved thermal compatibility with the substrate and an enhanced glass mediated self healing ability.