  Tunneling spin transport characteristics of a magnetic skyrmion are described
theoretically in magnetic scanning tunneling microscopy (STM). The
spin-polarized charge current in STM (SP-STM) and tunneling spin transport
vector quantities, the longitudinal spin current and the spin transfer torque,
are calculated in high spatial resolution within the same theoretical
framework. A connection between the conventional charge current SP-STM image
contrasts and the magnitudes of the spin transport vectors is demonstrated that
enables the estimation of tunneling spin transport properties based on
experimentally measured SP-STM images. A considerable tunability of the spin
transport vectors by the involved spin polarizations is also highlighted. These
possibilities and the combined theory of tunneling charge and vector spin
transport pave the way for gaining deep insight into electric-current-induced
tunneling spin transport properties in SP-STM and to the related dynamics of
complex magnetic textures at surfaces.
