Dresden 2020 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 1: Topological Insulators 1 (joint session TT/HL)

TT 1.10: Talk

Monday, March 16, 2020, 12:00–12:15, HSZ 03

Topological insulator interfaced with ferromagnetic insulators: Bi₂Te₃ thin films on magnetite and iron garnets — V. M. Pereira¹, S. G. Altendorf¹, C. E. Liu¹, S. C. Liao¹, A. C. Komarek¹, M. Guo², H. -J. Lin³, C. T. Chen³, M. Hong⁴, J. Kwo², L. H. Tjeng¹, and •C. N. Wu^1,2 — ¹MPI CPfS, Dresden, Germany — ²Dept. of Phys., NTHU, Hsinchu, Taiwan — ³NSRRC, Hsinchu, Taiwan — ⁴Dept. of Phys., NTU, Taipei, Taiwan

We report on our study about the growth and characterization of Bi₂Te₃ thin films on top of Y₃Fe₅O₁₂(111), Tm₃Fe₅O₁₂(111), Fe₃O₄(111), and Fe₃O₄(100) single crystal substrates. Using molecular beam epitaxy, we were able to prepare the topological insulator / ferromagnetic insulator heterostructures with no or minimal chemical reaction at the interface. We observed the anomalous Hall effect on these heterostructures and also a suppression of the weak antilocalization in the magnetoresistance, indicating a topological surface state gap opening induced by the magnetic proximity effect. However, we did not observe any obvious x-ray magnetic circular dichroism (XMCD) on the Te M₄₅ edges. The results suggest that the ferromagnetism induced by the magnetic proximity effect via Van der Waals bonding in Bi₂Te₃ is too weak to be detected by XMCD, but still can be observed by electrical transport measurements. This is in fact not inconsistent with reported density-functional calculations on the size of the gap opening.