Fig. 2: Experimentally-measured magnetic properties and surface electronic structure of MnBi2Te4.
From: Intrinsic magnetic topological insulators of the MnBi2Te4 family
a Magnetic susceptibility (left axis) of MnBi2Te4 as a function of temperature measured in an external magnetic field of μ0H = 1 T in zero-field-cooled (ZFC) and field-cooled-warming (FCW) conditions, alongside the temperature-dependent reciprocal susceptibility (right axis) for H⊥(0001). b High-field magnetization data of MnBi2Te4 at 4 and 30 K with the field applied either along the c axis or in the ab plane. HSF denotes the spin-flop magnetic field. Dispersion of the topological surface state of MnBi2Te4(0001) measured with (c) a conventional synchrotron ARPES (photon energy hν = 28 eV, T = 17 K) and (d, e) laser-ARPES (hν = 6.3 eV, T = 10 K). In (d, e) the data acquired on two samples synthesized by different groups are shown. In (e) the second derivative data, d2N(E)/dE2, are presented. Note the reduced intensity at the expected Dirac point position in (c), indicative of the gap, which is also seen in (e), while, in contrast, the Dirac cone is gapless in (d). In the inset to (c), the second derivative (d2N(E)/dE2) of the data taken with a more bulk sensitive photons (hν = 9 eV, T = 17 K) is presented, where the bulk valence and conduction bands, separated by a gap of about 0.2 eV190, can be seen. Magnetic structure of MnBi2Te4 below (f) and above (g) T*, see text for the explanation. Note that the intermixing levels are intentionally enhanced for the visualization purposes. h Compilation of the literature data on the Dirac point gap size, as measured by different groups using laser-ARPES. Only the data reported for T < TNéel are shown. Note that Shikin et al.58 report data on 15 different MnBi2Te4 samples, as shown by blue circles. a, c are reproduced with permission from ref. 26, Copyright Springer-Nature, 2019. b is reproduced with permission from ref. 45, Copyright American Physical Society, 2021. d is reproduced from ref. 49. e is reproduced with permission from ref. 58, Copyright American Physical Society, 2021.
