The charge-exchange spin-dipole (SD) and spin-quadrupole (SQ) strength functions of 90 Zr are calculated with and without the tensor terms of the Skyrme interaction in self-consistent HF+RPA approach. It is found that, in SD and SQ transitions, the RPA correlations associated with the tensor terms shin dramatically the strengths of ( Y l œÉ ) Œª = l ‚à? and ( Y l œÉ ) Œª = 1 modes upward and downward, respectively, and also shift the strengths of ( Y l œÉ ) Œª = l + 1 modes upward. The coupling between ( Y l = Œª ‚à?1 œÉ ) Œª and ( Y l = Œª + 1 œÉ ) Œª modes arising from the tensor correlation is noticeable. The RPA tensor correlations produce strengths of SD and SQ modes, which are distributed in a much wider energy range, and the ( Y l œÉ ) Œª = l ‚à?1 modes dominate the high energy part of the strength functions. These energy shifts and coupling effects of different modes can be understood qualitatively by expressing a finite range tensor force in a separable form.
An asymmetric single-nanoslit composed of a conventional nanoslit with a nanogroove next to it in a metallic film is proposed to generate unidirectional surface plasmon polaritons (SPPs) efficiently with back-side illumination. Numerical simulations show that due to the different interference processes of SPPs to opposite directions, efficient unidirectional SPP generation can be achieved. Experimentally, an extinction ratio of about 30:1 for SPPs to opposite directions and a generation efficiency of about 1.8 times that of the symmetrical case are demonstrated at wavelength of 830 nm with the lateral dimension of the asymmetric single-nanoslit of only 370 nm. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3472251]
