Efficient magnetic control of electronic conduction is at the heart of spintronic functionality for memory and logic applications1,2. Magnets with topological band crossings serve as a good material platform for such control, because their topological band degeneracy can be readily tuned by spin configurations, dramatically modulating electronic conduction3–10. Here we propose that the topological nodal-line degeneracy of spin-polarized bands in magnetic semiconductors induces an extremely large angular response of magnetotransport. Taking a layered ferrimagnet, Mn3Si2Te6, and its derived compounds as a model system, we show that the topological band degeneracy, driven by chiral molecular orbital states, is lifted depending on spin orientation, which leads to a metal–insulator transition in the same ferrimagnetic phase. The resulting variation of angular magnetoresistance with rotating magnetization exceeds a trillion per cent per radian, which we call colossal angular magnetoresistance. Our findings demonstrate that magnetic nodal-line semiconductors are a promising platform for realizing extremely sensitive spin- and orbital-dependent functionalities.
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Acknowledgements We thank H. W. Lee and J. Y. Kim for productive discussion. We also thank H. G. Kim from the Pohang Accelerator Laboratory (PAL) for technical support. This work was supported by the Institute for Basic Science (IBS) through the Center for Artificial Low Dimensional Electronic Systems (no. IBS-R014-D1), and by the National Research Foundation of Korea (NRF) through the SRC (grant no. 2018R1A5A6075964), and the Max Planck-POSTECH Center for Complex Phase Materials (grant no. 2016K1A4A4A01922028). H.H. was supported by Samsung Science and Technology Foundation under project number SSTF-BA2002-06. The pulsed field work was supported by the HLD at HZDR, member of the European Magnetic Field Laboratory (EMFL). K.K. was supported by the NRF (grant no. 2016R1D1A1B02008461), and the internal R&D programme at KAERI (no. 524460-21). B.-J.Y. was supported by the Institute for Basic Science in Korea (grant no. IBS-R009-D1), Samsung Science and Technology Foundation under project number SSTF-BA2002-06, and NRF grants funded by the Korea government (MSIT; no. 2021R1A2C4002773 and no. NRF-2021R1A5A1032996). J.H.K. acknowledges financial support from the NRF through grant no. NRF-2021R1A2C3004989 and grant no. 2017R1A5A1014862 (vdWMRC SRC Program). B.K. acknowledges support by the NRF through grant no. 2021R1C1C1007017. S.-W.C. was partially supported by the Center for Quantum Materials Synthesis (cQMS), funded by the Gordon and Betty Moore Foundation’s EPiQS initiative through grant GBMF10104, and by Rutgers University. A portion of this work was performed at the National High Magnetic Field Laboratory, which is supported by the National Science Foundation Cooperative agreement no. DMR-1644779 and the State of Florida.
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