Exploring new quantum phases in the interface between topological insulator and ferromagnet

2014 Fiscal Year Final Research Report

• Project/Area Number: 25871133
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Condensed matter physics II
• Research Institution: The Institute of Physical and Chemical Research
• Principal Investigator: KEI Takahashi 独立行政法人理化学研究所, 創発物性科学研究センター, 上級研究員 (90469932)
• Project Period (FY): 2013-04-01 – 2015-03-31
• Keywords: トポロジカル絶縁体 / 量子化異常ホール効果

Outline of Final Research Achievements

Buried Dirac electron between topological insulator (Bi,Sb)2Te3 and conventional semiconductor InP was investigated and Quantum anomalous Hall effect was observed in Cr-doped (Bi,Sb)2Te3 film. We found that the resonance tunneling current is oscillated corresponding to the Landau levels that exist at the interface induced by applied magnetic field. Ferromagnetic Cr-doped (Bi,Sb)2Te3 films were fabricated. At low temperatures, quantum anomalous Hall effect was clearly observed. By plotting parametric plot of conductance for various gate voltages, the quantized properties were found to be regarded as the same propertiy with conventional quantum Hall effect under a magnetic field. In addition, we controlled the top and bottom surface states to change the Landau filling factor in the bilayer composed of non-doped and Cr-doped (Bi,Sb)2Te3.

Free Research Field

薄膜物性実験