AVS 51st International Symposium
    Surface Science Monday Sessions
       Session SS1-MoM

Paper SS1-MoM7
Quantum Well States in Thin Films of Pb on Si(111)

Monday, November 15, 2004, 10:20 am, Room 210B

Session: Electronic Structure and Excitations
Presenter: J.H. Dil, Fritz-Haber-Institute der MPG, Germany
Authors: J.H. Dil, Fritz-Haber-Institute der MPG, Germany
J.W. Kim, Fritz-Haber-Institute der MPG, Germany
A. Mans, Delft University of Technology, The Netherlands
A.R.H.F. Ettema, Delft University of Technology, The Netherlands
K. Horn, Fritz-Haber-Institute der MPG, Germany
Correspondent: Click to Email
The Pb/Si(111) system shows a rich variety of interesting physical properties and phenomena, such as the magic height of islands, vertical Friedel oscillations @footnote 1@, a competition between classical and quantum mechanical effects in the shape relaxation @footnote 2@, anomalous optical absorption @footnote 3@ and an anomalous behaviour in the Hall effect as a function of thickness. Hence it is important to study the electronic structure of thin Pb films on Si(111) with a view to understanding the origin of these phenomena. Photoemission experiments carried out at the synchrotron radiation facilities of MAX-lab in Lund (Sweden) and BESSY in Berlin, from a large range of film thicknesses prepared under different conditions exhibit clear signatures of 2 D quantum well states. Their energy dispersion with parallel electron momentum show an anomalously large in-plane effective mass of the 2D quantum well state bands, with the highest effective masses for states near the Fermi level. This contrasts with effective masses of the bulk bands from which these states are derived, and with similar data from the Pb/Cu(111) system @footnote 4@; also, band structure calculations for bulk and thin film slabs predict bands with predominantly free electron character. Our analysis suggests that this phenomenon may be due to a strong electron correlation effect in the 2D bands of the Pb quantum well states. @FootnoteText@ @footnote 1@ W.B. Jian, W.B. Su, C.S. Chang, T.T.Tsong, Phys.Rev.Lett.90, 6603 (2003). @footnote 2@ H. Okamoto, D. Chen, T. Yamada , Physical Review Letters 89, 6101 (2002). @footnote 3@  M. Jalochowski et al., Physical Review B 66, 205417 (2002). @footnote 4@ J.H. Dil, J.W. Kim, S. Gokhale, M. Tallarida, K. Horn, PRB, in press.