Publication: Observation of a Mott insulating ground state for Sn/Ge(111) at low temperature
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2006-03-31
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American Physical Society
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We report an investigation on the properties of 0.33 ML of Sn on Ge(111) at temperatures down to 5 K. Low-energy electron diffraction and scanning tunneling microscopy show that the (3 x 3) phase formed at similar to 200 K, reverts to a new (root 3 x root 3)R30 degrees phase below 30 K. The vertical distortion characteristic of the (3 x 3) phase is lost across the phase transition, which is fully reversible. Angle-resolved photoemission experiments show that, concomitantly with the structural phase transition, a metal-insulator phase transition takes place. The (root 3 x root 3)R30 degrees ground state is interpreted as the formation of a Mott insulator for a narrow half-filled band in a two-dimensional triangular lattice.
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© 2006 The American Physical Society.
We acknowledge financial support from MCyT (Spain) under Grants No. MAT2003-08627-C0201 and No. FIS2005-0747. A. M. thanks the program ‘‘Ramón y Cajal.’’ R. C. thanks ‘‘Comunidad de Madrid’’ and ‘‘Fondo Social Europeo.’’ Part of this work was performed at the Swiss Light Source, Paul Scherrer Institut, Villigen, Switzerland. STM images have been analyzed using WSxM software from Nanotec.
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