  The motion of transverse domain walls (DWs) in U-shaped ferromagnetic
nanotube which owns two different geometric confinements were investigated by
micromagnetic simulation. Driven by unidirectional magnetic fields, the
chirality-dependent DW structure and velocity under low fields and two phases
of chiral Walker breakdown processes under high fields were observable,
respectively. All these chirality-dependent behaviors can be attributed to the
different dynamics of magnetizations in geometric confinements. Additionally,
DW structures have different responses and sensitivity to applied fields,
leading to a hierarchy and complex Walker breakdown processes. This supplies a
new perspective for manipulating DW chirality.
