Narrow Results

The electronic structure of silicene supported by monolayer of different monochalcogenide MX (GaS, GaSe, GaTe and InSe) substrates has been investigated by first principle density functional theory. By calculating the formation energies and phonons, it has been seen that silicene supported by monolayer of MX remains stable. The systems retain their almost $2D$ planner configurations with small buckling as that of the free standing silicene and also the Bader charge analysis shows that silicene hardly interacts with any of the MX substrates. The Dirac cone with a small gap ($\sim 30–50$ meV) has been observed in each of the cases. All the systems show quantum spin Hall effect and the quantum spin Hall conductivities have been estimated to be within the range $\sim 2-5\frac{\hslash }{e}$S/cm, which are larger than that of the free standing silicene. Our calculations show that even if the systems have bulk band gaps but the edge states are conducting in nature.

Spin waves (SWs) have been studied experimentally and by simulations in 1000 nm side equilateral triangular Permalloy dots in the Buckle state (B, with in-plane field along the triangle base) and the Y state (Y, with in-plane field perpendicular to the base). The excess of exchange energy at the triangles edges creates channels that allow effective spin wave propagation along the edges in the B state. These quasi one-dimensional SWs emitted by the vertex magnetic charges gradually transform from propagating to standing due to interference and (as pointed out by simulations) are weakly affected by small variations of the aspect ratio (from equilateral to isosceles dots) or by interdot dipolar interaction present in our dot arrays. SWs excited in the Y state have mainly a two-dimensional character. Propagation of the SWs along the edge states in triangular dots opens possibilities for creation of new and versatile spintronic devices.