Credit: Graduate School of Science and Engineering, Ehime University
Recently study on synthetic approaches toward polycyclic aromatic hydrocarbons (PAHs) as graphene with a well-defined structure has attracted much attention. A research group in Ehime University has been studying the synthesis and fundamental properties of pyrrole-fused azacoronene (HPHAC), a nitrogen-containing PAH. HPHACs are composed of electron-rich pyrroles, which are easily oxidized, and their dicationic species in particular exhibit unique features such as global aromaticity based on macrocyclic π-conjugation. However, all the compounds reported so far have bulky substituents at the periphery of the HPHAC skeleton, and thus the characterization of the physical properties of the pristine HPHAC itself or the π-electron function based on π-π interactions has not been possible.
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IMAGE: Scientists at SLAC National Accelerator Laboratory used an improved X-ray technique to explore exotic states of matter in an unconventional superconductor that conducts electricity with 100% efficiency at relatively high. view more
Credit: Jun-Sik Lee/SLAC National Accelerator Laboratory
Unconventional superconductors contain a number of exotic phases of matter that are thought to play a role, for better or worse, in their ability to conduct electricity with 100% efficiency at much higher temperatures than scientists had thought possible - although still far short of the temperatures that would allow their wide deployment in perfectly efficient power lines, maglev trains and so on.
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IMAGE: a Neutron diffraction patterns of CrBr3 measured at selected temperatures and refined by the Rietveld method. The experimental points and calculated profiles are shown. The ticks below represent the calculated. view more
Credit: Kazan Federal University
Two-dimensional (2D) materials with a single-layer thickness retaining magnetic order in atomically thin limit began to increase their scientific and technological significance after the successful synthesis of graphene and later investigations of van der Waals materials. CrBr3 has been known since the 60s as a van der Waals ferromagnet. Hansen, Tsubokawa, and Dillon have pioneered the work on magnetism in this compound. However, it has only recently been established that CrBr3 exhibits ferromagnetism when exfoliating to several layers and monolayers while saving its magnetic order. Nevertheless, no systematic experimental data simultaneously investigating the temperature behavior of the crystal, the magn
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IMAGE: a. Band structure of the bi-anisotropic effective medium model in the space of [k-45°, kz, ω]. The blue lines are band degeneracies. b. Band structure with kz = 0, nodal. view more
Credit: by Dongyang Wang, Biao Yang, Qinghua Guo, Ruo-Yang Zhang, Lingbo Xia, Xiaoqiang Su, Wen-Jie Chen, Jiaguang Han, Shuang Zhang, C. T. Chan
Topological photonics has attracted a lot of attention recently. The application of topological band theory to photonics not only opens the door to novel devices, but also stimulates the exploration of new topological phases. In the photonic regime, symmetries that are unique to electromagnetic (EM) waves can intrinsically protect the band degeneracies in the momentum space. Topological systems realized using such symmetries are uniquely photonic , having no counterparts in electronic or phononic systems.