Abstract
Small-angle neutron scattering has been applied to study the vortex lattice in the intercalated graphite superconductor . Scattering from the vortex lattice is in the form of a ring, most likely reflecting the absence of in-plane orientational order of the pyrolitic graphene planes. The temperature and field dependence of the scattered intensity allows the in-plane zero temperature value of the coherence length and the London penetration depth to be estimated. Measurements with the applied field at 70° to the axis directly reveal the penetration depth anisotropy, , which, unlike , is equal to the anisotropy of the coherence length deduced from magnetization measurements. The orientation of the vortex lattice is fixed relative to the rotation axis of the crystal as predicted by anisotropic London theory.
- Received 8 January 2007
DOI:https://doi.org/10.1103/PhysRevB.75.140516
©2007 American Physical Society