Extremely large magnetoresistance and Shubnikov-de Haas oscillations in topological semimetal FeGe₂

Extremely large magnetoresistance (XMR) observed in topological materials holds significant promise for spintronic applications. In this work, we systematically investigate the magnetotransport properties and quantum oscillations in high-quality single crystals of the magnetic nodal-line semimetal FeGe2. Synthesized via chemical vapor transport, the FeGe2 crystals exhibit an exceptional residual resistivity ratio of 533 and achieve a nonsaturating XMR of 23 000% at 1.8 K and 14 T, accompanied by ultrahigh carrier mobility (1 × 105 cm2 V−1 s−1). Shubnikov-de Haas oscillations reveal a π-Berry phase, suggesting a possible nontrivial topological nature of FeGe2. The remarkably high ratio of transport-to-quantum lifetimes (τtr/τQ ≈ 1571) further confirms suppression of backscattering, possibly related to topological protection. Combined with Hall effect measurements and extended Kohler scaling analysis, we establish that the origin of XMR in FeGe2 arises from the synergistic interplay between topological protection and high carrier mobility, rather than conventional electron-hole compensation. These findings not only provide critical experimental insights into the XMR mechanism of magnetic nodal-line semimetals but also highlight FeGe2 as a promising candidate for designing next-generation topological spintronic devices.