Chemical potential dependent gap-opening at the Dirac surface states of Bi2Se3 induced by aggregated substitutional Cr atoms

Abstract

With angle-resolved photoemission spectroscopy, gap-opening is resolved at up to room temperature in the Dirac surface states of molecular beam epitaxy grown Cr-doped Bi2Se3 topological insulator films, which however show no long-range ferromagnetic order down to 1.5 K. The gap size is found decreasing with increasing electron doping level. Scanning tunneling microscopy and first principles calculations demonstrate that substitutional Cr atoms aggregate into superparamagnetic multimers in Bi2Se3 matrix, which contribute to the observed chemical potential dependent gap-opening in the Dirac surface states without long-range ferromagnetic order.

20 pages, 4 figures

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• Magnetic proximity effect at Bi${}_2$Se${}_3$/EuS interface with broken inversion symmetry
• Direct evidence of ferromagnetism in MnSb2Te4
• Zero Magnetic Field Plateau Phase Transition in Higher Chern Number Quantum Anomalous Hall Insulators
• Breaking time reversal symmetry in topological insulators
• Superexchange dominates in magnetic topological insulators
• Ferromagnetic Anomalous Hall Effect in Cr-doped Bi${}_2$Se${}_3$ Thin Films via Surface-State Engineering
• Distinct Effects of Cr Bulk Doping and Surface Deposition on the Chemical Environment and Electronic Structure of the Topological Insulator Bi2Se3
• Dilute magnetic topological semiconductors: What's new beyond the physics of dilute magnetic semiconductors?
• Evolution of Dopant-Concentration-Induced Magnetic Exchange Interaction in Topological Insulator Thin Films
• Topological transitions to Weyl states in bulk Bi${}_2$Se${}_3$: Effect of hydrostatic pressure and doping
• Axion insulator, Weyl points, quantum anomalous Hall effect and magnetic topological phase transition in Eu3In2As4
• Phonon and defect mediated quantum anomalous Hall insulator to metal transition in magnetically doped topological insulators
• Interlayer Coupling-Induced Quantum Phase Transition in Quantum Anomalous Hall Multilayers
• Interlayer Exchange Coupling-Induced Critical-Metal-to-Insulator Phase Transition in Quantum Anomalous Hall Insulators