Abstract
Majorana zero-energy bound states have been proposed to exist at the ends of one-dimensional Rashba nanowires proximity-coupled to an s-wave superconductor in an external magnetic field1,2. Such hybrid structures are a central platform in the search for non-Abelian Majorana zero modes that may be applied in fault-tolerant topological quantum computing3,4. Here we report the discovery of zero-energy bound states simultaneously appearing at both ends of a one-dimensional atomic line defect in monolayer iron-based high-temperature superconductor FeTe0.5Se0.5 films. The spectroscopic properties of the zero-energy bound states, including the temperature and tunnelling barrier dependences, as well as their fusion induced by coupling on line defects of different lengths are found to be robust and consistent with those of the Majorana zero modes. These observations suggest a realization of topological Shockley defects at the ends of an atomic line defect in a two-dimensional s-wave superconductor that can host a Kramers pair of Majorana zero modes protected by time-reversal symmetry along the chain. Our findings reveal a class of topological line defect excitations in two-dimensional superconductor FeTe0.5Se0.5 monolayer films and offer an advantageous platform for generating topological zero-energy excitations at higher operating temperatures, in a single material, and under zero external magnetic field.
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References
Lutchyn, R. M., Sau, J. D. & Das Sarma, S. Majorana fermions and a topological phase transition in semiconductor–superconductor heterostructures. Phys. Rev. Lett. 105, 077001 (2010).
Oreg, Y., Refael, G. & von Oppen, F. Helical liquids and Majorana bound states in quantum wires. Phys. Rev. Lett. 105, 177002 (2010).
Alicea, J., Oreg, Y., Refael, G., von Oppen, F. & Fisher, M. P. A. Non-Abelian statistics and topological quantum information processing in 1D wire networks. Nat. Phys. 7, 412–417 (2011).
Nayak, C., Simon, S. H., Stern, A., Freedman, M. & Das Sarma, S. Non-Abelian anyons and topological quantum computation. Rev. Mod. Phys. 80, 1083–1159 (2008).
Kitaev, A. Y. Unpaired Majorana fermions in quantum wires. Phys. Uspekhi 44, 131 (2001).
Fu, L. & Kane, C. L. Superconducting proximity effect and Majorana fermions at the surface of a topological insulator. Phys. Rev. Lett. 100, 096407 (2008).
Beenakker, C. W. J. Search for Majorana fermions in superconductors. Annu. Rev. Condens. Mat. Phys. 4, 113–136 (2013).
Xu, J. P. et al. Experimental detection of a Majorana mode in the core of a magnetic vortex inside a topological insulator–superconductor Bi2Te3/NbSe2 heterostructure. Phys. Rev. Lett. 114, 017001 (2015).
Wang, D. F. et al. Evidence for Majorana bound states in an iron-based superconductor. Science 362, 333–335 (2018).
Machida, T. et al. Zero-energy vortex bound state in the superconducting topological surface state of Fe(Se,Te). Nat. Mater. 18, 811–815 (2019).
Zhang, P. et al. Observation of topological superconductivity on the surface of an iron-based superconductor. Science 360, 182–186 (2018).
Wang, Z. J. et al. Topological nature of the FeSe0.5Te0.5 superconductor. Phys. Rev. B 92, 115119 (2015).
Xu, G., Lian, B., Tang, P. Z., Qi, X. L. & Zhang, S. C. Topological superconductivity on the surface of Fe-based superconductors. Phys. Rev. Lett. 117, 047001 (2016).
Yin, J. X. et al. Observation of a robust zero-energy bound state in iron-based superconductor Fe(Te,Se). Nat. Phys. 11, 543–546 (2015).
Jiang, K., Dai, X. & Wang, Z. Q. Quantum anomalous vortex and Majorana zero mode in iron-based superconductor Fe(Te,Se). Phys. Rev. X 9, 011033 (2019).
Mourik, V. et al. Signatures of Majorana fermions in hybrid superconductor–semiconductor nanowire devices. Science 336, 1003–1007 (2012).
Das, A. et al. Zero-bias peaks and splitting in an Al–InAs nanowire topological superconductor as a signature of Majorana fermions. Nat. Phys. 8, 887–895 (2012).
Deng, M. T. et al. Anomalous zero-bias conductance peak in a Nb–InSb nanowire–Nb hybrid device. Nano Lett. 12, 6414–6419 (2012).
Zhang, H. et al. Quantized Majorana conductance. Nature 556, 74–79 (2018).
Law, K. T., Lee, P. A. & Ng, T. K. Majorana fermion induced resonant Andreev reflection. Phys. Rev. Lett. 103, 237001 (2009).
Wimmer, M., Akhmerov, A. R., Medvedyeva, M. V., Tworzydlo, J. & Beenakker, C. W. J. Majorana bound states without vortices in topological superconductors with electrostatic defects. Phys. Rev. Lett. 105, 046803 (2010).
Li, F. S. et al. Interface-enhanced high-temperature superconductivity in single-unit-cell FeTe1-xSex films on SrTiO3. Phys. Rev. B 91, 220503 (2015).
Nichele, F. et al. Scaling of Majorana zero-bias conductance peaks. Phys. Rev. Lett. 119, 136803 (2017).
Liu, C. et al. Detection of a zero energy bound state induced on high temperature superconducting one-unit-cell FeSe on SrTiO3. Preprint at https://arxiv.org/abs/1807.07259 (2018).
Setiawan, F., Liu, C. X., Sau, J. D. & Das Sarma, S. Electron temperature and tunnel coupling dependence of zero-bias and almost-zero-bias conductance peaks in Majorana nanowires. Phys. Rev. B 96, 184520 (2017).
Qi, X. L., Hughes, T. L., Raghu, S. & Zhang, S. C. Time-reversal-invariant topological superconductors and superfluids in two and three dimensions. Phys. Rev. Lett. 102, 187001 (2009).
Zhang, F., Kane, C. L. & Mele, E. J. Time-reversal-invariant topological superconductivity and Majorana Kramers pairs. Phys. Rev. Lett. 111, 056402 (2013).
Nadj-Perge, S. et al. Observation of Majorana fermions in ferromagnetic atomic chains on a superconductor. Science 346, 602–607 (2014).
Kim, H. et al. Toward tailoring Majorana bound states in artificially constructed magnetic atom chains on elemental superconductors. Sci. Adv. 4, eaar5251 (2018).
Alff, L. et al. Spatially continuous zero-bias conductance peak on (110) YBa2Cu3O7-δ surfaces. Phys. Rev. B 55, R14757–R14760 (1997).
Sato, M., Tanaka, Y., Yada, K. & Yokoyama, T. Topology of Andreev bound states with flat dispersion. Phys. Rev. B 83, 224511 (2011).
Shi, X. et al. FeTe1−xSex monolayer films: towards the realization of high-temperature connate topological superconductivity. Sci. Bull. 62, 503–507 (2017).
Wei, P., Manna, S., Eich, M., Lee, P. & Moodera, J. Superconductivity in the surface state of noble metal gold and its Fermi level tuning by EuS dielectric. Phys. Rev. Lett. 122, 247002 (2019).
Wang, Q. Y. et al. Interface-induced high-temperature superconductivity in single-unit-cell FeSe films on SrTiO3. Chin. Phys. Lett. 29, 037402 (2012).
Qi, X. L., Hughes, T. L. & Zhang, S. C. Topological invariants for the Fermi surface of a time-reversal-invariant superconductor. Phys. Rev. B 81, 134508 (2010).
Acknowledgements
This work was supported by the National Natural Science Foundation of China (no. 11888101), the National Key Research and Development Program of China (2018YFA0305604 and 2017YFA0303302), the National Natural Science Foundation of China (no. 11774008), the Strategic Priority Research Program of the Chinese Academy of Sciences (grant no. XDB28000000), the Beijing Natural Science Foundation (Z180010) and the US Department of Energy, Basic Energy Sciences (grant no. DE-FG02–99ER45747: K.J. and Z.W.).
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J.W. conceived and supervised the research. C.C. grew the samples and analysed the experimental data. C.C., C.L. and Y.L. carried out the STM/STS experiments. K.J., Y.Z. and Z.W. proposed the theoretical model and performed the theoretical analysis and calculations. C.C., Z.W. and J.W. wrote the manuscript with comments from all authors.
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Chen, C., Jiang, K., Zhang, Y. et al. Atomic line defects and zero-energy end states in monolayer Fe(Te,Se) high-temperature superconductors. Nat. Phys. 16, 536–540 (2020). https://doi.org/10.1038/s41567-020-0813-0
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DOI: https://doi.org/10.1038/s41567-020-0813-0
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