NMR Probing Spin Excitations in the Ring-Like Structure of a Two-Subband System

Resistively detected nuclear magnetic resonance (NMR) is observed inside the ring-like structure, with a quantized Hall conductance of 6e^2/h, in the phase diagram of a two subband electron system. The NMR signal persists up to 400 mK and is absent in other states with the same quantized Hall conductance. The nuclear spin-lattice relaxation time, T1, is found to decrease rapidly towards the ring center. These observations are consistent with the assertion of the ring-like region being a ferromagnetic state that is accompanied by collective spin excitations.Comment: 4 pages, 4 figure

The unique chemical reactivity of a graphene nanoribbon's zigzag edge

The zigzag edge of a graphene nanoribbon possesses a unique electronic state that is near the Fermi level and localized at the edge carbon atoms. We investigate the chemical reactivity of these zigzag edge sites by examining their reaction energetics with common radicals from first principles. A "partial radical" concept for the edge carbon atoms is introduced to characterize their chemical reactivity, and the validity of this concept is verified by comparing the dissociation energies of edge-radical bonds with similar bonds in molecules. In addition, the uniqueness of the zigzag-edged graphene nanoribbon is further demonstrated by comparing it with other forms of sp2 carbons, including a graphene sheet, nanotubes, and an armchair-edged graphene nanoribbon.Comment: 24 pages, 9 figure

Phenomenological Implications of Supersymmetric Family Non-universal U(1)-prime Models

We construct a class of anomaly-free supersymmetric U(1)' models that are characterized by family non-universal U(1)' charges motivated from E_6 embeddings. The family non-universality arises from an interchange of the standard roles of the two SU(5) 5* representations within the 27 of E_6 for the third generation. We analyze U(1)' and electroweak symmetry breaking and present the particle mass spectrum. The models, which include additional Higgs multiplets and exotic quarks at the TeV scale, result in specific patterns of flavor-changing neutral currents in the b to s transitions that can accommodate the presently observed deviations inthis sector from the SM predictions.Comment: 25 pages, 3 figure

Bank ownership, privatization, and performance: evidence from a transition country

This paper combines the static effect of ownership and the dynamic effect of privatization on bank performance in China over 1995-2010, reporting a significantly higher performance by private intermediaries – joint stock commercial banks and city commercial banks – relative to state-owned commercial banks. However, publicly traded banks, subject to multiple monitoring and vetting in capital markets, perform better regardless of ownership status. The privatization of banks has improved performance with respect to revenue inflow and efficiency gains in the short- or long-run (initial public offerings). The positive long-run effect is more relevant and significant for banking institutions with minority foreign ownership. Moreover, this paper innovatively estimates interest income efficiency and non-interest income efficiency at the same time. The results suggest that Chinese banks are much more efficient in generating interest income than raising non-interest revenue, although the latter aspect has improved significantly during the sample period

Corporate governance and bank performance in China

This paper examines the effects of corporate governance on bank performance in China over the period 1995-2008. Bank performance has improved significantly and the mean profit efficiency level is estimated at 61 per cent. The results suggest that differences in corporate governance have significant impacts on bank performance: banks with majority foreign ownership are most profitable while banks with majority state ownership are most unprofitable. We find no evidence that foreign minority ownership in domestic banks improves performance. Banks with more dispersed ownership are found to be more profit efficient