Prediction of flat bands in a ternary intermetallic electride LaCoSi

Abstract

Paramagnetic LaCoSi, a ternary intermetallic electride, consists of CoSi blocks separated by two layers of La atoms. Its structure is similar to that of the widely studied 111 system of iron-based superconductors. Utilizing angle-resolved photoemission spectroscopy and first-principles calculations, we demonstrate the existence of linear bands and flat bands mainly originating from the e_g orbitals of Co 3d states near the Fermi energy. The anomalous scattering rate of the linear bands varies linearly with the binding energy. The flat band above the Fermi energy indicated by the calculations could be modulated by substitutions and pressure to induce new ordered quantum phases, such as magnetism and superconductivity. Our findings reveal flat-band physics in electrides.

Graphical abstract

Keywords

electronic structure / flat bands / ARPES / electride

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Declarations

The authors declare that they have no competing interests and there are no conflicts.

Acknowledgements

This work was supported by the National Key R&D Program of China (Grant No. 2022YFB3608000), the National Natural Science Foundation of China (NSFC) (Grant Nos. 12222413 and 12074041), the Natural Science Foundation of Shanghai (Grant Nos. 23ZR1482200 and 22ZR1473300), the Funding of Ningbo Yongjiang Talent Program, the Natural Science Foundation of Ningbo, Ningbo University (No. LJ2024003), the Postdoctoral Fellowship Program of CPSF (Grant No. GZC20240951), the Natural Science Foundation of Shandong Province (Grant Nos. ZR2021QA031, ZR2023MA068, and ZR2024QA213), the Qingdao Postdoctoral Project Funding (No. QDBSH20240102115), and the Fundamental Research Funds for the Central Universities (Grant No. 2243300003).

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