Dirac fermions and flat bands in the ideal kagome metal FeSn

Mingu Kang; Linda Ye; Shiang Fang; Jhih Shih You; Abe Levitan; Minyong Han; Jorge I. Facio; Chris Jozwiak; Aaron Bostwick; Eli Rotenberg; Mun K. Chan; Ross D. McDonald; David Graf; Konstantine Kaznatcheev; Elio Vescovo; David C. Bell; Efthimios Kaxiras; Jeroen van den Brink; Manuel Richter; Madhav Prasad Ghimire; Joseph G. Checkelsky; Riccardo Comin

doi:10.1038/s41563-019-0531-0

Dirac fermions and flat bands in the ideal kagome metal FeSn

Mingu Kang, Linda Ye, Shiang Fang, Jhih Shih You, Abe Levitan, Minyong Han, Jorge I. Facio, Chris Jozwiak, Aaron Bostwick, Eli Rotenberg, Mun K. Chan, Ross D. McDonald, David Graf, Konstantine Kaznatcheev, Elio Vescovo, David C. Bell, Efthimios Kaxiras, Jeroen van den Brink, Manuel Richter, Madhav Prasad GhimireJoseph G. Checkelsky^*, Riccardo Comin

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

405 Citations (Scopus)

Abstract

A kagome lattice of 3d transition metal ions is a versatile platform for correlated topological phases hosting symmetry-protected electronic excitations and magnetic ground states. However, the paradigmatic states of the idealized two-dimensional kagome lattice—Dirac fermions and flat bands—have not been simultaneously observed. Here, we use angle-resolved photoemission spectroscopy and de Haas–van Alphen quantum oscillations to reveal coexisting surface and bulk Dirac fermions as well as flat bands in the antiferromagnetic kagome metal FeSn, which has spatially decoupled kagome planes. Our band structure calculations and matrix element simulations demonstrate that the bulk Dirac bands arise from in-plane localized Fe-3d orbitals, and evidence that the coexisting Dirac surface state realizes a rare example of fully spin-polarized two-dimensional Dirac fermions due to spin-layer locking in FeSn. The prospect to harness these prototypical excitations in a kagome lattice is a frontier of great promise at the confluence of topology, magnetism and strongly correlated physics.

Original language	English
Pages (from-to)	163-169
Number of pages	7
Journal	Nature Materials
Volume	19
Issue number	2
DOIs	https://doi.org/10.1038/s41563-019-0531-0
Publication status	Published - 2020 Feb 1
Externally published	Yes

ASJC Scopus subject areas

General Chemistry
General Materials Science
Condensed Matter Physics
Mechanics of Materials
Mechanical Engineering

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Kang, M., Ye, L., Fang, S., You, J. S., Levitan, A., Han, M., Facio, J. I., Jozwiak, C., Bostwick, A., Rotenberg, E., Chan, M. K., McDonald, R. D., Graf, D., Kaznatcheev, K., Vescovo, E., Bell, D. C., Kaxiras, E., van den Brink, J., Richter, M., ... Comin, R. (2020). Dirac fermions and flat bands in the ideal kagome metal FeSn. Nature Materials, 19(2), 163-169. https://doi.org/10.1038/s41563-019-0531-0

Kang, M, Ye, L, Fang, S, You, JS, Levitan, A, Han, M, Facio, JI, Jozwiak, C, Bostwick, A, Rotenberg, E, Chan, MK, McDonald, RD, Graf, D, Kaznatcheev, K, Vescovo, E, Bell, DC, Kaxiras, E, van den Brink, J, Richter, M, Prasad Ghimire, M, Checkelsky, JG & Comin, R 2020, 'Dirac fermions and flat bands in the ideal kagome metal FeSn', Nature Materials, vol. 19, no. 2, pp. 163-169. https://doi.org/10.1038/s41563-019-0531-0

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abstract = "A kagome lattice of 3d transition metal ions is a versatile platform for correlated topological phases hosting symmetry-protected electronic excitations and magnetic ground states. However, the paradigmatic states of the idealized two-dimensional kagome lattice—Dirac fermions and flat bands—have not been simultaneously observed. Here, we use angle-resolved photoemission spectroscopy and de Haas–van Alphen quantum oscillations to reveal coexisting surface and bulk Dirac fermions as well as flat bands in the antiferromagnetic kagome metal FeSn, which has spatially decoupled kagome planes. Our band structure calculations and matrix element simulations demonstrate that the bulk Dirac bands arise from in-plane localized Fe-3d orbitals, and evidence that the coexisting Dirac surface state realizes a rare example of fully spin-polarized two-dimensional Dirac fermions due to spin-layer locking in FeSn. The prospect to harness these prototypical excitations in a kagome lattice is a frontier of great promise at the confluence of topology, magnetism and strongly correlated physics.",

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AU - Levitan, Abe

AU - Han, Minyong

AU - Facio, Jorge I.

AU - Jozwiak, Chris

AU - Bostwick, Aaron

AU - Rotenberg, Eli

AU - Chan, Mun K.

AU - McDonald, Ross D.

AU - Graf, David

AU - Kaznatcheev, Konstantine

AU - Vescovo, Elio

AU - Bell, David C.

AU - Kaxiras, Efthimios

AU - van den Brink, Jeroen

AU - Richter, Manuel

AU - Prasad Ghimire, Madhav

AU - Checkelsky, Joseph G.

AU - Comin, Riccardo

PY - 2020/2/1

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N2 - A kagome lattice of 3d transition metal ions is a versatile platform for correlated topological phases hosting symmetry-protected electronic excitations and magnetic ground states. However, the paradigmatic states of the idealized two-dimensional kagome lattice—Dirac fermions and flat bands—have not been simultaneously observed. Here, we use angle-resolved photoemission spectroscopy and de Haas–van Alphen quantum oscillations to reveal coexisting surface and bulk Dirac fermions as well as flat bands in the antiferromagnetic kagome metal FeSn, which has spatially decoupled kagome planes. Our band structure calculations and matrix element simulations demonstrate that the bulk Dirac bands arise from in-plane localized Fe-3d orbitals, and evidence that the coexisting Dirac surface state realizes a rare example of fully spin-polarized two-dimensional Dirac fermions due to spin-layer locking in FeSn. The prospect to harness these prototypical excitations in a kagome lattice is a frontier of great promise at the confluence of topology, magnetism and strongly correlated physics.

AB - A kagome lattice of 3d transition metal ions is a versatile platform for correlated topological phases hosting symmetry-protected electronic excitations and magnetic ground states. However, the paradigmatic states of the idealized two-dimensional kagome lattice—Dirac fermions and flat bands—have not been simultaneously observed. Here, we use angle-resolved photoemission spectroscopy and de Haas–van Alphen quantum oscillations to reveal coexisting surface and bulk Dirac fermions as well as flat bands in the antiferromagnetic kagome metal FeSn, which has spatially decoupled kagome planes. Our band structure calculations and matrix element simulations demonstrate that the bulk Dirac bands arise from in-plane localized Fe-3d orbitals, and evidence that the coexisting Dirac surface state realizes a rare example of fully spin-polarized two-dimensional Dirac fermions due to spin-layer locking in FeSn. The prospect to harness these prototypical excitations in a kagome lattice is a frontier of great promise at the confluence of topology, magnetism and strongly correlated physics.

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Dirac fermions and flat bands in the ideal kagome metal FeSn

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