Controlling the magneto-transport properties of magnetic topological insulator thin films from Cr${}_x$(Bi${}_y$Sb${}_{1-y}$)${}_{2-x}$Te${}_3$ via molecular beam epitaxy

Abstract

In this work we present a systematic in-depth study of how we can alter the magneto-transport properties of magnetic topological insulator thin films by tuning the parameters of the molecular beam epitaxy. First, we show how a varying substrate temperature changes the surface morphology and when chosen properly leads to a high crystal quality. Next, the effect of the chromium concentration on the film roughness and crystal quality is investigated. Finally, both the substrate temperature and the chromium concentration are investigated with respect to their effect on the magneto-transport properties of the magnetic topological insulator thin films. It becomes apparent that the substrate temperature and the chromium concentration can be used to tune the Fermi level of the film which allows to make the material intrinsically charge neutral. A very low chromium concentration furthermore allows to tune the magnetic topological insulator into a regime where strong superconducting correlations can be expected when combining the material with a superconductor.

15 pages, 8 figures

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