Direct Observations of Structural Phase Transitions in Planar Crystallized Ion Plasmas
T. B. Mitchell,
*
J. J. Bollinger,
D. H. E. Dubin,
X.-P. Huang,
W. M. Itano,
R. H. Baughman
Laser-cooled 9Be+ ions confined in
two-dimensionally extended lattice planes were directly observed, and
the images were used to characterize the structural phases of the ions.
Five different stable crystalline phases were observed, and the
energetically favored structure could be sensitively tuned by changing
the areal density of the confined ions. The experimental results are in good agreement with theoretical predictions for the planar (infinite in
two dimensions) one-component plasma. Qualitatively similar structural
phase transitions occur, or are predicted to occur, in other
experimentally realizable planar systems.
T. B. Mitchell, J. J. Bollinger, X.-P. Huang, W. M. Itano, Time and Frequency Division, National Institute of Standards and
Technology, Boulder, CO 80303, USA. D. H. E. Dubin,
Department of Physics, University of California at San Diego, La Jolla,
CA 92093, USA. R. H. Baughman, Research and Technology, Allied
Signal, Morristown, NJ 07962, USA.
*
To whom correspondence should be addressed. E-mail:
travis.mitchell{at}nist.gov
