SUPERCONDUCTING FLUX LATTICE IN A STRONG MAGNETIC-FIELD IN THE HIGH-TC SUPERCONDUCTORS

In a strong magnetic field (flux lattice constant much smaller than penetration depth), vibrations of the vortex lattice are found to decouple from those of the applied field. This suggests that three-dimensional effects (vortex bending) are much more important than in previous theories. A modified Lindemann criterion shows that the vanishing of critical currents in the high-Tc superconductors can be well described by flux lattice melting, with numerical fits yielding estimates for Hc2 which agree with the most recent previous values. The Lindemann criterion is found to be insensitive to the effective-mass anisotropy of the material except at high fields. In analysing the dispersion relation for the combined field-vortex oscillations, Doppler-shifted cyclotron resonance of core electrons is found to provide a roton-like minimum.