Charge-density waves observed with a tunneling microscope

Abstract

Charge-density waves on cleaved surfaces of 1T-${\mathrm{TaS}}_{2}$ appeared at 77 K as hexagonal arrays of mounds with spacings of (3.5\ifmmode\pm\else\textpm\fi{}0.3)${\mathrm{a}}_{0}$, where ${\mathrm{a}}_{0}$=3.346 A\r{} is the lattice spacing of the 1T-${\mathrm{TaS}}_{2}$. In contrast, cleaved surfaces of 2H-${\mathrm{TaSe}}_{2}$ at 77 K showed only atoms. The tunneling microscope was operated under liquid nitrogen with a ${\mathrm{Pt}}_{0.8}$${\mathrm{Ir}}_{0.2}$ tip for both types of samples.