  We consider a model in which the soft gamma-ray repeaters (SGRs) result from
young, magnetized strange stars with superconducting cores. As such a strange
star spins down, the quantized vortex lines move outward and drag the magnetic
field tubes because of the strong coupling between them. Since the terminations
of the tubes interact with the stellar crust, the dragged tubes can produce
sufficient tension to crack the crust. Part of the broken platelet will be
dragged into the quark core, which is only $10^4$ cm from the surface, leading
to the deconfinement of crustal matter into strange quark matter and thus the
release of energy. We will show that the burst energy, duration, time interval
and spectrum for our model are in agreement with the observational results. The
persistent X-ray emission from the SGRs can be well explained by our model.
