We study theoretically the RKKY interaction between magnetic impurities on the surface of three-dimensional topological insulators, mediated by the helical Dirac electrons. Exact analytical expression shows that the RKKY interaction consists of the Heisenberg-like, Ising-like, and Dzyaloshinskii-Moriya (DM)-like terms. It provides us a new way to control surface magnetism electrically. The gap opened by doped magnetic ions can lead to a short-range Bloembergen-Rowland interaction. The competition among the Heisenberg, Ising, and DM terms leads to rich spin configurations and an anomalous Hall effect on different lattices.

We study Dirac plasmons and their damping in spatially separated N -layer graphene structures at finite doping and temperatures. The plasmon spectrum consists of one optical excitation with a square-root dispersion and N − 1 acoustical excitations with linear dispersions, which are undamped at zero temperature within a triangular energy region outside the electron-hole continuum. For any finite number of graphene layers we have found that the energy and weight of the optical plasmon increase in the long wavelength limit, respectively, as square-root and linear functions of N . This is in agreement with recent experimental findings. With an increase of the number of multilayer acoustical plasmon modes, the energy and weight of the upper lying branches also exhibit an enhancement with N . This increase is strongest for the uppermost acoustical mode so that its energy can exceed at some value of momentum the plasmon energy in an individual graphene sheet. Meanwhile, the energy of the low lying acoustical branches decreases weakly with N as compared with the single acoustical mode in double-layer graphene structures. Our numerical calculations provide a detailed understanding of the overall behavior of the wave vector dependence of the optical and acoustical multilayer plasmon modes and show how their dispersion and damping are modified as a function of temperature, interlayer spacing, and inlayer carrier density in (un)balanced graphene multilayer structures.

The poor stability of the zinc‐metal anode is a main bottleneck for practical application of aqueous zinc‐ion batteries. Herein, a series of molecular sieves with various channel sizes are investigated as an electrolyte host to regulate the ionic environment of Zn2+ on the surface of the zinc anode and to realize separator‐free batteries. Based on the ZSM‐5 molecular sieve, a solid–liquid mixed electrolyte membrane is constructed to uniformize the transport of zinc ions and foster dendrite‐free Zn deposition. Side reactions can also be suppressed through tailoring the solvation sheath and restraining the activity of water molecules in electrolyte. A V2O5||ZSM‐5||Zn full cell shows significantly enhanced performance compared to cells using glass fiber separator. Specifically, it exhibits a high specific capacity of 300 mAh g−1, and a capacity retention of 98.67% after 1000 cycles and 82.67% after 3000 cycles at 1 A g−1. It is attested that zeolites (ZSM‐5, H‐β, and Bate) with channel sizes of 5–7 Å result in best cycle stability. Given the low cost and recyclability of the ZSM and its potent function, this work may further lower the cost and boost the industrial application of AZIBs.

No abstract