We investigate the atomic structure of (n = 9-14) clusters using the first-principles pseudopotential method within the local-density-functional approximation (LDA). The equilibrium geometries of small clusters with tend to be capped prismatic structures. For n = 13, we find a surface-like metallic compact structure which is derived from a capped icosahedron and competes with a stable trigonal prism, while this structure is the most stable for n = 14. These results are compatible with the observed stability of and , as compared to clusters with nearby values of n, against chemical reactions with simple molecules. The effect of electron-electron correlations on the energetics of isomers with n = 13 is examined through variational quantum Monte Carlo calculations, and the LDA energy ordering remains unchanged, consistently with previous diffusion quantum Monte Carlo calculations.

We present the anomalous magnetotransport observed in a narrow high mobility Hall device; both the peaks and minima in the Shubnikov-de Haas oscillations of the longitudinal resistance appear in the quantized plateau region of the Hall resistance. We interpret this feature as a consequence of an inhomogeneous distribution of two dimensional electron gas and provide a quantitative view with a model based on the edge current picture.