Quantum oscillations and quasilinear magnetoresistance in the topological semimetal candidate Sc Sn 2

Novel compounds with two-dimensional square lattices formed by group IV or V elements (Si, Sn, Ge, Bi, and Sb) have been attracting a great deal of attention in recent times, mainly because of the possible emergence of various topological phases therein. Here, we successfully grow the single crystals of Sn-square-net based material $\mathrm{Sc}{\mathrm{Sn}}_{2}$, and systematically perform their magnetization and magnetotransport measurements. Clear quantum oscillations emerge in the magnetization isotherms along different field orientations, from which nonzero Berry phases are extracted, implying that $\mathrm{Sc}{\mathrm{Sn}}_{2}$ harbors three-dimensional Fermi surfaces and nontrivial electronic states. Similar to many other topological semimetals with extremely large magnetoresistance, $\mathrm{Sc}{\mathrm{Sn}}_{2}$ shows field-induced resistivity enhancement as well, which has been proven to be not of a gap opening origin. Besides, at low temperature, large magnetoresistance with a quasilinear field dependence is observed. Our analysis of the magnetotransport data finds that the quasilinear magnetoresistance in $\mathrm{Sc}{\mathrm{Sn}}_{2}$ cannot be understood by several familiar mechanisms proposed in the literature. These findings are expected to have far reaching implications for both the fundamental understanding and magnetoresistance device application of topological semimetal materials.