Identification of a two-dimensional surface charge-density-wave transition in Sn/Cu(100)

J. MARTÍNEZ BLANCO; V. JOCO; H. ASCOLANI; A. TEJEDA; C. QUIRÓS; G. PANACCIONE; T. BALASUBRAMANIAN; P. SEGOVIA; E.G. MICHEL

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

Año: 2005 vol. 72 p. 414011 - 414014

0163-1829

We identify and characterize a two-dimensional phase transition in a layer of Sn on Cu(100). The stable phase at room temperature has a (3Ö 2 x Ö 2 ) R45° structure. Above 360 K, a new phase with (3Ö 2 x Ö 2 ) R45° structure is formed. The high-temperature phase exhibits a quasi-two-dimensional free-electron surface band, with Fermi surface nesting in excellent agreement with the three-times larger periodicity of the low-temperature phase. A momentum-dependent band gap opens along the nested areas of the Fermi surface in the low-temperature phase. The phase transition is a clear experimental confirmation of the role of Fermisurface gapping and nesting in the stabilization of a commensurate two-dimensional phase, which is interpreted as a charge-density wave.