  In the mixed state of layered superconductor the antiferromagnetic order of
magnetic ions can create the spin-flop domains along the phase cores of the
Josephson vortices. The paper discusses how this feature affects the
macroscopic quantum tunnelling of the Josephson vortices. It is shown that the
action and hence the activation energy is rendered temperature dependent so
that the quantum tunnelling rate becomes temperature dependent below the
crossover temperature. It is also shown that in constant temperature thermal or
quantum creep may occur, depending on the direction or intensity of the applied
magnetic field.
