  In this paper, we report on the investigation of (1) the transport properties
of multi-carriers in semi-metal Bi and (2) the spin conversion physics in this
semimetal system in a ferrimagnetic insulator, yttrium-iron-garnet. Hall
measurements reveal that electrons and holes co-exist in the Bi, with electrons
being the dominant carrier. The results of a spin conversion experiment
corroborate the results of the Hall measurement; in addition, the inverse spin
Hall effect governs the spin conversion in the semimetal/insulator system. This
study provides further insights into spin conversion physics in semimetal
systems.
