Abstract
In this work, we employed angle resolved photoemission spectroscopy (ARPES) to analyze the temperature dependent changes in the electronic structure of the first antiferromagnetic topological insulator MnBi2Te4 upon crossing the Néel temperature TN ≈ 25 K. We observed an exchange splitting of the bulk conduction band, which has a power law dependence on temperature (1−T/T0)2β with an onset temperature T0 well matching the measured bulk TN. We found a matching temperature evolution of the topological surface states integrated spectral weight in the vicinity of the Dirac point. Furthermore, we observed an additional quasi-2D state with Rashba-type splitting, which is also affected by the emerged magnetism and exhibits an opening of a gap, reminiscent of the effect of an out-of-plane magnetic field, below TN. All these findings point toward strong evidence of the interplay between emerged magnetism with bulk and topological surface states. The observed temperature-dependent effects in MnBi2Te4 may be used as an experimental fingerprint for the presence of magnetism and may guide the future analysis of ARPES spectra in magnetic topological insulators.
Highlights
T0 well matching the measured bulk TN
When time reversal symmetry (TRS) is broken via exchange interactions, the topological surface states (TSS) are no longer protected, and a gap opens at the Dirac point (DP)
Here we present a detailed study of the electronic structure in paramagnetic (PM) and AFM phases in MBT by means of μ-focused Laser-based angle resolved photoemission spectroscopy (ARPES)
Summary
We observed an exchange splitting of the bulk conduction band, which has a power law dependence on temperature with an onset temperature We found a matching temperature evolution of the topological surface states integrated spectral weight in the vicinity of the Dirac point.
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