Competition between surface reaction and diffusion of gold deposited onto ZrTe3

2003

Abstract Surface reaction and diffusion of gold, deposited onto the (0 0 1) ZrTe 3 van der Waals (vdW) surface, is studied by transmission electron and scanning tunneling microscopy. It is shown that both processes compete at temperatures as low as room temperature. In case of diffusion the deposited gold mostly disappears from the surface and intercalates into the vdW gaps of the substrate. Residual unreacted gold agglomerates are rather mobile and are often displaced by the scanning tip along the [1 0 0] direction of the substrate. In case of reaction, which usually takes place at somewhat higher substrate temperatures, grains of Zr 3 Te 2 , AuTe 2 and/or Au 2 Te 3 are formed. Contrary to…

Charge density waves in NbSe3: The models and the experimental evidence

2010

a b s t r a c t Charge density wave (CDW) ordering in the prototypical low-dimensional compound NbSe3 is reconsidered. It is shown that the model with two incommensurate modulations, q1 = (0, 0.241, 0) and q2 = (0.5, 0.260, 0.5), localized on type-III and type-I bi-capped trigonal prismatic columns, does not explain details, revealed by various microscopic methods. An alternative explanation, based on the existence of modulated layered nano-domains below both CDW onset temperatures, is suggested. It accounts for the presence of the q2 modulation in the STM images recorded above the T2 CDW transition and for the absence of q2 satellites in the corresponding diffraction patterns. The long per…

STM evidence of room-temperature charge instabilities inNbSe3

1996

${\mathrm{NbSe}}_{3}$ is a quasi-low-dimensional compound with unique properties. Two incommensurate charge-density waves appear at low temperatures, which slide under the application of an electric field. The mechanism of sliding is not fully understood and it was speculated that precursor effects may be present above the onset temperatures. Scanning tunneling microscopy offers a unique tool to search for such charge instabilities and clear evidence is given for their existence at room temperature. \textcopyright{} 1996 The American Physical Society.

Enhanced CDW Transitions in Nb3X4(X = S, Se, Te): Intercalation and Surface Effects

2004

A x Nb 3 X 4 (A = In, Tl, ZnHg; X = S, Se, Te) compounds show CDW instabilities dependent on the type and concentration of intercalate. Tl or In intercalation flattens the Fermi surfaces and supports CDW formation. In the corresponding DOS spectrum the Fermi level is shifted towards coincidence with a small peak, derived mainly from the Nb dz 2 orbital. Localized modulated regions observed in STM images of Nb 3 X 4 at room temperature represent precursor effects to full CDW formation.

The Instability of the NbTe2 Surface Structure

2002

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.

Alternative model for the structural modulation inNbSe3andm−TaS3

2001