  It is shown that the electric charge of vortices can result in a helical
instability of straight vortex lines in layered superconductors, particularly
Bi-based cuprates or organic superconductors. This instability may result in a
phase transition to a uniformly twisted vortex state, which could be detected
by torque magnetometry, neutron diffraction, electromagnetic or calorimetric
measurements.

Superconductivity