Fig. 2: Room temperature nano-imaging of CrSBr waveguide modes.
From: Hyperbolic exciton polaritons in a van der Waals magnet
Room temperature near-field images at, (a) \(E=1.49{{{{{\rm{eV}}}}}}\) and, (b) \(E=1.27{{{{{\rm{eV}}}}}}\) showing interference fringes along \(a\)- and \(b\)-axes of a \(117{{{{{\rm{nm}}}}}}\) CrSBr microcrystal. c, line profiles along the white dashed \(b\)-axis line in (a) at probe energies from \(E=1.26-1.55{{{{{\rm{eV}}}}}}\). A region of negative dispersion (black dashed line) is observed near the exciton resonance (\({{{{{\rm{X}}}}}}\)). d Line profiles along the \(a\)-axis line in (a) have a positive linear dispersion (black dashed line) throughout the \(E=1.26-1.55{{{{{\rm{eV}}}}}}\) energy range. e Geometry-corrected Fourier peaks of line profiles in (c, d) overlaid on the \({{{{{\rm{Im}}}}}}\) \({r}_{p}\) loss function calculated using optical constants from far-field spectroscopy. s-SNOM data are consistent with the vacuum light cone and waveguide mode dispersions. The waveguide mode dispersion backbends near \({{{{{\rm{X}}}}}}\) only along the \(b\)-axis.
