  We consider the effect that a change in the magnetic induction B has in
causing an orbitally quantized field-induced spin- or charge density wave
(FISDW or FICDW) state to depart from thermodynamic equilibrium. The
competition between elastic forces of the density wave (DW) and pinning leads
to the realization of a critical state that is in many ways analogous to that
realized within the vortex state of type II superconductors. Such a critical
state has been verified experimentally in charge-transfer salts of the
composition alpha-(BEDT-TTF)MHg(SCN)4, but should be a generic property of all
orbitally quantized DW phases. The metastable state consists of a balance
between the DW pinning force and the Lorentz force on extended currents
associated with drifting cyclotron orbits, resulting in the establishment of
persistent currents throughout the bulk and to the possibly of a
three-dimensional `chiral metal' that extends deep into the interior of a
crystal.
