Dresden 2020 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 8: Topological Phenomena (joint session MA/TT)

TT 8.2: Vortrag

Montag, 16. März 2020, 09:45–10:00, POT 6

Large magnetic gap at the Dirac point and spin polarization control in Bi2Te3/MnBi2Te4 heterostructures — •Friedrich Freyse1, Emile Rienks1, Stefan Wimmer2, Andreas Ney2, Hubert Steiner2, Valentine Volobuev2, Heiko Groiss2, Günther Bauer2, Andrei Varykhalov1, Oliver Rader1, Gunther Springholz2, and Jaime Sánchez-Barriga11Helmholtz-Zentrum Berlin für Materialien und Energie, BESSY II, Berlin, Germany — 2Institut für Halbleiter und Festkörperphysik, Johannes Kepler Universität, Linz, Austria

Using spin- and angle-resolved photoemission, we investigate the electronic and spin structure of the topological surface state (TSS) of Bi2Te3/MnBi2Te4 heterostructures as a function of temperature. By cooling below the Curie temperature TC, we observe how a magnetic surface gap opens at the Dirac point of the initially gapless TSS, a requirement which is crucial to enable the quantum anomalous Hall effect. The spectrum of the gapped Dirac point measured in remanence after field cooling (M+) is clearly spin polarized, with spin orientation perpendicular to the surface plane and spin split by a large value of Δ = 56 ± 4 meV at 6 K. Subsequent measurement at room temperature shows that the spin polarization completely disappears, whereas subsequent cooling in an oppositely oriented field (M-) leads to a reversal of the spin polarization.

[1] J.Sánchez-Barriga et al. Nature (2019), in press

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