Berlin 2018 – scientific programme

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O: Fachverband Oberflächenphysik

O 32: Electronic structure of surfaces: Spectroscopy, surface states I

O 32.6: Talk

Tuesday, March 13, 2018, 15:15–15:30, MA 004

Systematics of electronic and magnetic properties in the transition metal-doped quantum anomalous Hall platform Sb₂Te₃ — •Johannes Jung¹, M. Bode¹, P. Sessi¹, S. Schatz¹, T.R.F. Peixoto¹, H. Bentmann¹, F. Reinert¹, A. Barla², M.F. Islam³, A. Pertsova⁴, A. Balastky⁴, and C. M. Canali³ — ¹Physikalisches Institut, Universität Würzburg, Am Hubland, Würzburg, Germany — ²Istituto di Struttura della Materia, Trieste, Italy — ³Department of Physics,Linnaeus University, Kalmar, Sweden — ⁴Nordita, Stockholm University, Sweden

The quantum anomalous Hall effect has been reported to emerge in magnetically doped topological insulators. While its phenomenological description is quite clear, its microscopic origins are far from being completely understood and controlled. Here, we provide a systematic characterization of the most prominent QAHE platform: transition metal-doped Sb₂Te₃. By combing complementary experimental techniques (STM/STS/resPES/XMCD) with ab-initio theory, we analyze how 3d dopants (V, Cr, Mn, Fe) impact the electronic and magnetic properties. Our results reveal that the fate of the topological surface state strongly depends on the specific character of the 3d impurity. In particular, (i) the single-ion magnetic anisotropy, which controls the magnetic gap opening and its stability, can vary from in-plane to out-of-plane depending on the dopant; (ii) the emergence of impurity resonances close to the Dirac point can give rise to new bands, significantly altering the Sb₂Te₃ electronic structure. Overall, our results provide general guidelines for the realization of a robust QAHE.