AVS 50th International Symposium
    Nanometer Structures Thursday Sessions
       Session NS-ThM

Paper NS-ThM8
Real-Space Imaging of the Vortex Lattice in V@sub 3@Si Using Low Temperature Scanning Tunneling Microscopy*

Thursday, November 6, 2003, 10:40 am, Room 308

Session: Advances in Scanning Probes
Presenter: J.A. Stroscio, National Institute of Standards and Technology
Authors: J.A. Stroscio, National Institute of Standards and Technology
C.E. Sosolik, National Institute of Standards and Technology
M.D. Stiles, National Institute of Standards and Technology
E.W. Hudson, Massachusetts Institute of Technology
S.R. Blankenship, National Institute of Standards and Technology
A.P. Fein, National Institute of Standards and Technology
R.J. Celotta, National Institute of Standards and Technology
Correspondent: Click to Email
In Type II superconductors, the expulsion of an applied magnetic field from the superconductor, the Meissner effect, is not complete for fields above the lower critical field. In this applied field regime, magnetic flux penetrates the superconductor as quantized vortices that interact through shielding currents. In equilibrium the vortices form a lattice with symmetry, and orientation relative to the crystallographic axes, determined by microscopic electronic properties. In this talk we present low temperature scanning tunneling microscopy measurements of the structural evolution of the vortex lattice in a single-crystal V@sub 3@Si sample. Large-scale conductance maps obtained at 2.3 K provide a real-space image of the vortex lattice formed with a magnetic field applied parallel to the [001] crystal axis. Atomic resolution topography of the V@sub 3@Si (001) surface shows the underlying Si sublattice and allows for a determination of the orientation of the measured vortex lattice relative to the underlying crystal axes. The conductance maps reveal a change in the symmetry of the vortex lattice from hexagonal to nearly square over the field range of 0 T to 4 T. A strong anisotropy in the long-range translational order of the vortex lattice is observed near the transition field of 4 T. These observations give evidence for nonlocal electrodynamics in the vortex-vortex interactions of this Type II superconductor. Calculations that account for the role of these nonlocal effects in determining the structure and symmetry of the vortex lattice are presented and compared to our experimental results. * This work is supported in part by the Office of Naval Research.