Self-assembled, semimetallic ErSb single crystal nanostructures, grown by molecular beam epitaxy, are embedded within a semiconductor GaSb matrix. Formation, evolution and orientation of a variety of nanostructures, including spherical nanoparticles,
elongated nanorods, octagonal shaped nanowires oriented along the surface normal and nanowires oriented in the growth plane, are controlled simply by the Er fraction. The plasmonic properties of the semimetal/semiconductor composites are characterized and quantified by three polarization-resolved spectroscopy techniques, spanning more than three orders of magnitude in frequency from 100 GHz up to 300 THz. The effect of the size, shape and orientation of the nanostructures is characterized by polarization-sensitive response and modeled by a Maxwell-Garnett effective medium theory.
We construct explicit solutions for the linearized massive and massless spin-2, vector and scalar modes around the AdS spacetimes in diverse dimensions. These modes may arise in extended (super)gravities with higher curvature terms in general dimensi
ons. Log modes in critical gravities can also be straightforwardly deduced. We analyze the properties of these modes and obtain the tachyon-free condition, which allows negative mass square for these modes. However, such modes may not satisfy the standard AdS boundary condition and can be truncated out from the spectrum.
