  We theoretically study the current-induced dynamics of a domain wall in a
ferromagnetic nanotube by developing a theory for the orbital angular momentum
of a domain wall and the current-induced torque on it. Specifically, a domain
wall with nontrivial magnetization winding along the circumference is shown to
possess finite orbital angular momentum, which is proportional to the product
of its Skyrmion charge and position, and the current is shown to exert a torque
changing the orbital angular momentum of the domain wall and thereby drives it.
The current-induced torque is interpreted as the transfer of orbital angular
momentum from electrons to the domain wall, which occurs due to the emergent
magnetic field associated with the Skyrmion charge. Our results reveal a
hitherto unrecognized utility of the orbital degree of freedom of magnetic
solitons.
