Modulation of spin accumulation by nanoscale confinement using electromigration in a metallic lateral spin valve.

We study spin transport in lateral spin valves with constricted channels. Using electromigration, we modulate the spin accumulation by continuously varying the width of the non-magnetic (NM) channel at a single location. By fitting the non-local spin signal data as a function of the NM channel resistance, we extract all the relevant parameters regarding spin transport from a single device. Simulations show that constricting the channel blocks the diffusion of the accumulated spins rather than causing spin flipping. This result could be used to improve the design of future spintronic devices devoted to information processing.

Visualizing the near-field coupling and interference of bonding and anti-bonding modes in infrared dimer nanoantennas.

We directly visualize and identify the capacitive coupling of infrared dimer antennas in the near field by employing scattering-type scanning near-field optical microscopy (s-SNOM). The coupling is identified by (i) resolving the strongly enhanced nano-localized near fields in the antenna gap and by (ii) tracing the red shift of the dimer resonance when compared to the resonance of the single antenna constituents. Furthermore, by modifying the illumination geometry we break the symmetry, providing a means to excite both the bonding and the "dark" anti-bonding modes. By spectrally matching both modes, their interference yields an enhancement or suppression of the near fields at specific locations, which could be useful in nanoscale coherent control applications.

Real-space mapping of Fano interference in plasmonic metamolecules.

An unprecedented control of the spectral response of plasmonic nanoantennas has recently been achieved by designing structures that exhibit Fano resonances. This new insight is paving the way for a variety of applications, such as biochemical sensing and surface-enhanced Raman spectroscopy. Here we use scattering-type near-field optical microscopy to map the spatial field distribution of Fano modes in infrared plasmonic systems. We observe in real space the interference of narrow (dark) and broad (bright) plasmonic resonances, yielding intensity and phase toggling between different portions of the plasmonic metamolecules when either their geometric sizes or the illumination wavelength is varied.