  We study transport phenomena of total angular momentum in holography, as a
first step toward holographic understanding of spin transport phenomena. Spin
current, which has both the local Lorentz index for spins and the space-time
vector index for current, couples naturally to the bulk spin connection.
Therefore the bulk spin connection becomes the source for the boundary spin
current. This allows us to evaluate the spin current holographically, with a
relation to the stress tensor and metric fluctuations in the bulk. We examine
the spin transport coefficients and the thermal spin Hall conductivity in a
simple holographic setup.
