STM Program - Highlights
Mesoscopic Superconductors
Figure - STM topography (left) and CITS image of
vortices in a single crystal NbSe2 superconductor with periodic
array of normal pinning centers. The applied magnetic field is 8 times the
matching field (650 Oe) at T=4.2 K.
Nanoscale superconductors are close to being
accepted for widespread use in communications and power distribution. The main
reasons for this advancement is the ability to control the shape and structure
of the material on mesoscopic scale (the scale of superconducting coherence
length or penetration depth). Nanoscale engineered superconductors are easier
to cool because their mass is negligible and they are orders of magnitude more
resistant to the destructive effect of the magnetic field.
The mesoscopic effects based on the interaction
of magnetic vortices with artificial nano-engineered defects in the
superconductor is the focus of this program. We have developed unique methods
to engineer the materials and image vortex distribution in superconductors
using scanning tunneling microscopy. Detection of Abrikosov vortices by
measuring local density of states in the material (STM spectroscopy) provides
orders of magnitude better spatial resolution than any tool based on magnetic
signature of the vortex. This allows us to correlate the electronic modulation
in the material on atomic scale with spatial vortex phase transitions occurring
due to these modulations.
Recent Publications:
- Direct Observation of Vortex Lattice Transitions in Mesoscopic
Superconducting Single Crystals, Goran Karapetrov, Jan Fedor, Maria
Iavarone, Dan Rosenmann, and W.K. Kwok,
Phys. Rev. Lett.
95, p.167002 (2005)
- Imaging of Vortex States in Mesoscopic Superconductors, G.
Karapetrov, J. Fedor, M. Iavarone, M.T. Marshall, R. Divan,
Appl. Phys. Lett.
87, p.162515 (2005)
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