Bitter decoration of vortex structure in MgB2 single crystals

The Bitter decoration technique has been used to observe vortices in the superconducting state of single crystal MgB2. Experiments in low applied magnetic field (B≈4.4 G) allow for the estimation of the London penetration depth, λ, to be approximately 1900 A for T≈6 K. Experiments in higher applied fields (B≈200 G) unambiguously show a triangular vortex lattice in both real space (a larger than 10 μm ×10 μm image of over 1000 vortices) as well as in reciprocal space.