Unconventional resistivity scaling in topological semimetal CoSi

Nontrivial band topologies in semimetals lead to robust surface states that can contribute dominantly the total conduction. This may result reduced resistivity with decreasing feature size contrary conventional metals, which highly impact semiconductor industry. Here we study scaling of a representative topological semimetal CoSi using realistic structures and Green's function methods. We show there exists critical thickness d_c dividing different trends. Above d_c, when defect density is low such conduction dominates, reduces thickness; high bulk increases as metals. Below persistent remnants give rise down ultrathin limit, unlike insulators. The observed apply broad classes semimetals, providing guidelines for materials screening engineering. Our shows bear potential overcoming challenges back-end-of-line interconnect applications.