| In the presence of a spin-polarized electric current in a magnetic metal, a net angular momentum can be transfered from the spin of the itinerant electrons to the magnetization -- a process known as spin-transfer torque. In the field of spintronics, this effect is used to manipulate magnetic textures in nanomagnets like, for example, domain walls and vortices. Much less studied, however, is the influence of current on the magnetization in bulk materials. Especially interesting in this respect are helical magnets because they sustain stable inhomogeneous magnetic textures like skyrmions and lattices thereof, which can couple efficiently to an applied spin current. We study the influence of spin-transfer torques on such extended structures and, in particular, present a theory for the additional transfer of angular momentum to the orbital degrees of the magnetic texture via rotational torques. We apply the theory to MnSi where a spatial rotation of its skyrmion lattice induced by an electric current has been recently observed experimentally. |
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