The mechanism of re-entrant flux reversal in Fe-Si-B amorphous wires w
as investigated by domain observation and reverse domain detection foc
using on the magnetic properties near the wire ends. It was found that
the wire consists of shell and core domains and that the core region
has the residual reversing domain due to demagnetizing field near wire
ends in a remanent state.The residual domain was stabilized by formin
g a flux closure structure through the shell domain, which increases t
he threshold field for domain growth to a value much larger than the w
all coercivity and results in predominantly re-entrant flux reversal.