Origin of Orientation-Controlled Magnetoresistance\nAnisotropy in Topologically Protected Semimetal Bi Films

Topological\nsemimetallic materials have been widely studied in\nlow-dissipation electron transport and spintronics due to the potential\nspintronic topology. Current analysis in the electromagnetic transport\nof the topological semimetals focuses on single-crystal films. In\nthis work, the growth characteristics and magnetoresistance effect\non topological semimetal polycrystalline Bi are reported. Experimental\nresults show that polycrystalline Bi films contain high-quality crystallinity,\npreferred orientation out of plane, and random orientation in plane.\nMoreover, the preferred orientation reveals the transport phenomenon\nand origin of magnetoresistance anisotropy in polycrystalline Bi films.\nIn particular, Bi films grown in the coexisting (003) and (012) orientations\nshow a negative magnetoresistance change trend at low temperatures.\nTherefore, this work provides a strategy to control the magnetoresistance\nanisotropy and the abnormal Hall effect in polycrystalline films.