Hourglass Dirac Chain Metal in Rhenium Dioxide

Nonsymmorphic symmetries, which involve fractional lattice translations in crystalline materials, can generate exotic types of fermionic excitations that are robust against spin-orbit coupling. Here we report on a hourglass-type dispersion in the bulk of three-dimensional rhenium dioxide crystals, as dictated by its nonsymmorphic symmetries. Due to time reversal and inversion symmetries, each band has an additional two-fold degeneracy, making the neck crossing-point of the hourglass four-fold degenerate. Remarkably, close to the Fermi level, the neck crossing-point traces out a Dirac chain--a chain of connected four-fold-degenerate Dirac loops--in the momentum space. The symmetry protection, the transformation under symmetry-breaking, and the associated topological surface states of the hourglass Dirac chain are discussed.Comment: 5 pages, 5 figure

Financial planning and household portfolio performance: evidence from the 1998-2013 survey of consumer finances

This dissertation used datasets from the 1998, 2001, 2004, 2007, 2010 and 2013 Survey of Consumer Finances (SCF) to evaluate the effect of using financial planning services on households' portfolio performance. In this dissertation, portfolio performance was measured by portfolio Sharpe Ratio. Financial planning services were considered to be the professional services provided by lawyers, accountant and financial planners in this dissertation. After controlling other factors, the findings lend empirical support to the belief that financial planning service delivered by professionals benefit households in higher possibility of reaching better portfolio performance. This lends empirical support to claims that professional financial planning services provide value to clients. Implications for individual investors, financial planning professionals, and future research are discussed