Light-Tunable Surface State and Hybridization Gap in Magnetic Topological Insulator MnBi${}_8$Te${}_{13}$

Abstract

MnBi${}_8$Te${}_{13}$ is an intrinsic ferromagnetic (FM) topological insulator with different complex surface terminations. Resolving the electronic structures of different termination surfaces and manipulation of the electronic state are important. Here, by using micrometer spot time- and angle-resolved photoemission spectroscopy ($\mu$-TrARPES), we resolve the electronic structures and reveal the ultrafast dynamics upon photoexcitation. Photoinduced filling of the surface state hybridization gap is observed for the Bi${}_2$Te${}_3$ quintuple layer directly above MnBi${}_2$Te${}_4$ accompanied by a nontrivial shift of the surface state, suggesting light-tunable interlayer interaction. Relaxation of photoexcited electrons and holes is observed within 1-2 ps. Our work reveals photoexcitation as a potential control knob for tailoring the interlayer interaction and surface state of MnBi${}_8$Te${}_{13}$.

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Cited by in corpus (3)

• Ultrafast time- and angle-resolved photoemission spectroscopy with widely tunable probe photon energy of 5.3-7.0 eV for investigating dynamics of three-dimensional materials
• Facet dependent surface energy gap on magnetic topological insulators
• A sample-position-autocorrection system with precision better than 1 \um~in angle-resolved photoemission experiments