Negative longitudinal magnetoresistance and anomalous hall effect in the topological semimetal CoSi

The chiral semimetal cobalt monosilicide (CoSi) has recently attracted considerable attention because of its nearly ideal topological properties of the electron system. Hosting only two chiral fermions in the Brillouin zone, CoSi exhibits long Fermi arcs of maximum length, which are orders of magnitude larger than those found in other chiral Weyl fermion semimetals. Moreover, CoSi possesses a remarkably large topologically non-trivial energy window, allowing the measurement of topological chiral fermions without the need for fine-tuning the Fermi level position. We have studied the electrical transport behavior of CoSi crystals looking at various magneto-transport effects. These comprise angle-dependent magnetoresistance and quantum oscillations, Hall effect, and temperature-dependent resistivity studies. In combination, we gather some evidence for the remarkable lifetime of chiral carriers in this system.