|This is a poster that was created by Phyllis Green in the Condensed Matter Sciences Division at ORNL to commemorate my receiving the Welch Award in 2001. This award was given for my research in the last ten years previous years, which has shifted to the study of surface phase transition and especially exotic phenomena that occur at the surfaces of correlated electron materials such as the transition metal oxides.
In the area of surface phase transitions our most cited papers are those reporting on the nature of the phase transition for a submonolayer metallic film of Sn or Pb on Si(111) or Ge(111). In these systems defects are dynamic participants in the phase trasnsion. A few of the key papers are:
- Direct Observation of a Surface Charge Density Wave, J. M. Carpinelli, H. H. Weitering, E. W. Plummer and R. Stumpf, Nature 381, 398 (1996).
- Defect-Mediated Condensation of a Charge Density Wave, H. H. Weitering, J. M. Carpinelli, A. V. Melechko, Jiandi Zhang, M. Bartkowiak and E. W. Plummer, Science 285, 2107-2110 (1999).
- Direct visualization of Defect Density Waves in 2D, L. Ottaviano, A. V. Melechko, S. Santucci, and E. W. Plummer, Phys. Rev. Lett. 86, 1809 (2001).
The study of surface behavior in highly correlated materials has lead to some discoveries of absolutely new phases at the surface, either due to reconstruction or segregation.
- Ferromagnetism Stabilized by Lattice Distortion at the Surface of the p-wave superconductor Sr2RuO4, R. Matzdorf, Ismail, Jiandi Zhang, T. Kimura, Y. Tokura, Z. Fang, K. Terakura, and E. W. Plummer, Science 289, 746 (2000).
- Surface Segregation and Restructuring of CMR Manganese Perovskites: La0.65Sr0.35MnO3, Hani Dulli, P. A. Dowben, S.-H. Liou, and E. W. Plummer, Phys. Rev B 77, 570 (2000).
Most of these investigations involve the use of a variable temperature Scanning Tunneling Microscope. In collaboration with Bessenbacher in Denmark and Bradshaw in Germany we used low temperature STMS to study "Waves on Surfaces," created by two dimensional screening of defects.
- Giant Surface Friedel Oscillations, P. T. Sprunger, L. Petersen, E. W. Plummer, E. Laegsgaard, and F. Besenbacher, Science 275, 1764 (1997).
- Anisotropic two-dimensional Friedel oscillations, Ph. Hofmann, B. G. Briner, M. Doering, H.-P. Rust, E. W. Plummer, A. M. Bradshaw, Phys. Rev. Letters 79, 265-268 (1997).
- Looking at Electronic Wave Functions on Metal Surfaces, B. G. Briner, Philip Hofmann, M. Doering, H.-P. Rust, A. M. Bradshaw, L. Petersen, P. Sprunger, E. Laegsgaard, F. Besenbacher, E. W. Plummer, Europhysics News 28, 148 (1997).