Emile D. L. Rienks, S. Wimmer, Jaime Sanchez-Barriga, O. Caha, Partha Sarathi Mandal, J. Ruzicka, A. Ney, H. Steiner, V. V. Volobuev, H. Groiss, M. Albu, G. Kothleitner, J. Michalicka, S. A. Khan, J. Minar, H. Ebert, G. Bauer, Friedrich Freyse, Andrei Varykhalov, Oliver Rader, Gunther Springholz
- Magnetically doped topological insulators enable the quantum anomalous Hall effect (QAHE), which provides quantized edge states for lossless charge-transport applications(1-8). The edge states are hosted by a magnetic energy gap at the Dirac point(2), but hitherto all attempts to observe this gap directly have been unsuccessful. Observing the gap is considered to be essential to overcoming the limitations of the QAHE, which so far occurs only at temperatures that are one to two orders of magnitude below the ferromagnetic Curie temperature, T-C (ref. (8)). Here we use low-temperature photoelectron spectroscopy to unambiguously reveal the magnetic gap of Mn-doped Bi2Te3, which displays ferromagnetic out-of-plane spin texture and opens up only below T-C. Surprisingly, our analysis reveals large gap sizes at 1 kelvin of up to 90 millielectronvolts, which is five times larger than theoretically predicted(9). Using multiscale analysis we show that this enhancement is due to a remarkable structure modification induced by Mn doping: insteadMagnetically doped topological insulators enable the quantum anomalous Hall effect (QAHE), which provides quantized edge states for lossless charge-transport applications(1-8). The edge states are hosted by a magnetic energy gap at the Dirac point(2), but hitherto all attempts to observe this gap directly have been unsuccessful. Observing the gap is considered to be essential to overcoming the limitations of the QAHE, which so far occurs only at temperatures that are one to two orders of magnitude below the ferromagnetic Curie temperature, T-C (ref. (8)). Here we use low-temperature photoelectron spectroscopy to unambiguously reveal the magnetic gap of Mn-doped Bi2Te3, which displays ferromagnetic out-of-plane spin texture and opens up only below T-C. Surprisingly, our analysis reveals large gap sizes at 1 kelvin of up to 90 millielectronvolts, which is five times larger than theoretically predicted(9). Using multiscale analysis we show that this enhancement is due to a remarkable structure modification induced by Mn doping: instead of a disordered impurity system, a self-organized alternating sequence of MnBi2Te4 septuple and Bi2Te3 quintuple layers is formed. This enhances the wavefunction overlap and size of the magnetic gap(10). Mn-doped Bi2Se3 (ref. (11)) and Mn-doped Sb2Te3 form similar heterostructures, but for Bi2Se3 only a nonmagnetic gap is formed and the magnetization is in the surface plane. This is explained by the smaller spin-orbit interaction by comparison with Mn-doped Bi2Te3. Our findings provide insights that will be crucial in pushing lossless transport in topological insulators towards room-temperature applications.…
MetadatenAuthor details: | Emile D. L. RienksORCiD, S. Wimmer, Jaime Sanchez-BarrigaORCiDGND, O. Caha, Partha Sarathi MandalORCiD, J. Ruzicka, A. Ney, H. Steiner, V. V. Volobuev, H. Groiss, M. Albu, G. Kothleitner, J. Michalicka, S. A. Khan, J. Minar, H. Ebert, G. Bauer, Friedrich FreyseORCiD, Andrei VarykhalovORCiDGND, Oliver RaderORCiDGND, Gunther Springholz |
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DOI: | https://doi.org/10.1038/s41586-019-1826-7 |
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ISSN: | 0028-0836 |
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ISSN: | 1476-4687 |
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Pubmed ID: | https://pubmed.ncbi.nlm.nih.gov/31853081 |
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Title of parent work (English): | Nature : the international weekly journal of science |
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Publisher: | Nature Publ. Group |
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Place of publishing: | London |
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Publication type: | Article |
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Language: | English |
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Date of first publication: | 2019/12/18 |
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Publication year: | 2019 |
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Release date: | 2021/06/15 |
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Volume: | 576 |
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Issue: | 7787 |
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Number of pages: | 19 |
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First page: | 423 |
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Last Page: | 428 |
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Funding institution: | Austrian Science Fund (FWF)Austrian Science Fund (FWF) [P30969-N27, P28185-N27]; Austrian Federal Ministry for Digital and Economic Affairs; National Foundation for Research, Technology and Development of the Christian Doppler Laboratory for Nanoscale Phase Transformations; Deutsche ForschungsgemeinschaftGerman Research Foundation (DFG) [SPP 1666, SFB 1143, SFB 1277]; Central European Institute of Technology (CEITEC) Nano research infrastructure [LM2015041]; Computational and Experimental Design of Advanced Materials with New Functionalities (CEDAMNF) of the Czech Ministerstvo Skolstvi Mladeze a Telovychovy (MSMT) [CZ.02.1.01/0.0/0.0/15_00 3/0000358]; Impuls-und Vernetzungsfonds der Helmholtz-Gemeinschaft (Virtual Institute New States of Matter and their Excitations); Impuls-und Vernetzungsfonds der Helmholtz-Gemeinschaft (Helmholtz-Russia Joint Research Group) [HRSF-0067]; European Union Horizon 2020 programme [823717-ESTEEM3] |
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Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie |
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DDC classification: | 5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik |
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Peer review: | Referiert |
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Publishing method: | Open Access / Green Open-Access |
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