Scanning tunneling microscopy of charge-density waves in NbSe3.

The charge-density wave (CDW) structure in ${\mathrm{NbSe}}_{3}$ due to the two independent CDW's has been imaged by scanning microscopy. As predicted by band-structure considerations, the CDW modulation is observed to be substantially localized on different chains for the separate CDW's. AT 77 K where only the high-temperature CDW exists, a relatively weak modulation with a single component along the b axis is observed. At 4.2 K the low-temperature CDW contributes a much stronger \ensuremath{\sim}${4\mathrm{b}}_{0}$\ifmmode\times\else\texttimes\fi{}${2\mathrm{c}}_{0}$ superlattice modulation.