RESUMEN
The interplay between band topology and magnetism plays a central role in achieving exotic physical phenomena and innovative spintronics applications. While prior works have mainly focused on ferromagnetic matter, little is known about the manipulation of band topology in antiferromagnets. Here, we report the emergence of a two-dimensional (2D) antiferromagnetic topological insulator (AFM TIs) by proximity coupling a 2D TI and a normal AFM insulator, and remarkably realize it in a concrete example of the KCuSe/NaMnBi heterobilayer. The first-principles calculations show that a band gap as large as 63.8 meV can be opened up by spin-orbit coupling, revealing the possible application even at room temperature. The size of the band gap depends on the separation between KCuSe and NaMnBi QLs, which can be switched experimentally by applying external strain. Moreover, the heterobilayer presents an integer topological invariant with a value of Z2 = 1 and a pair of gapless edge states. The findings not only broaden the range of 2D AFM topological quantum materials, but could also inspire more research in van der Waals heterobilayers for topological spintronics.
RESUMEN
Fourier transform large amplitude alternating current voltammetry (FTACV) studies are reported on an electrocatalytic (EC') mechanistic system which exhibits split wave behavior on both macro- and micro-size working electrodes. The electrochemical characteristics of the EC' mechanism were analysed using the fundamental to fourth harmonic components deduced by the Fourier transform algorithm. The effects of the sinusoidal frequencies of the applied potential, electrode geometry and substrate concentrations are investigated. The split wave phenomenon was observed and explored particularly.
RESUMEN
This article reports a novel method to assemble a small anion with exfoliated Mg-Al-layered double hydroxide (LDH) nanosheets into ordered ultrathin films (UTFs) by employing the layer-by-layer assembly technique. The premixing solution of tris(8-hydroxyquinolate-5-sulfonate)aluminum(III) (AQS(3-)) with three kinds of polyanions-poly(acrylic acid), ((C(3)H(4)O(2))(n), PAA), poly(styrene 4-sulfonate) ([CH(2)CH(C(6)H(4))SO(3)](m), PSS), and poly[5-methoxy-2-(3-sulfopropoxy)-1,4-phenylene vinylene] (C(12)H(13)O(5)S)(n), PPV)-has been used as building blocks to assemble alternatively with LDH nanosheets. The UV-vis absorption and fluorescence spectroscopy of (AQS-polyanion/LDH)(n) UTFs presents stepwise growth upon increasing deposited cycles in comparison with the (AQS/LDH)(n) film under the same experimental process. (AQS-PPV/LDH)(n) UTF displays complex fluorescence originating from AQS and PPV. The (AQS/LDH)(n) and (AQS-polyanion/LDH)(n) UTFs exhibit higher blue-polarized photoemission character with a luminescence anisotropy (r) of ca. 0.12-0.20 and a longer fluorescence lifetime than that of the Na(3)AQS film with r = 0.04. X-ray diffraction, scanning electron microscopy, and atomic force microscopy demonstrated that the UTFs were orderly periodically layered structures with a thickness of ca. 3.0 nm per bilayer. Therefore, this work gives a feasible method for immobilizing small anions into the gallery of LDHs.