The Instability of the NbTe2 Surface Structure

Low energy electron diffraction from clean NbTe 2 surfaces shows very diffuse reflections. The effect is attributed to an anisotropic heating of the irradiated Te-Nb-Te surface layer. Diffraction patterns for electron energies below 90 eV correspond to an overlapped contribution from numerous domains, belonging to three orientational variants. Electrons of higher energies stabilize the parent high-temperature CdI 2 structure. A similar effect is observed during scanning tunneling microscopy, where the expected surface corrugation is usually lost for tunneling currents of a few ten nA.