Quantum anomalous Hall effect in heterostructure thin films of magnetic topological insulator

Aalto Quantum Physics Seminars (Hybrid) Minoru Kawamura (RIKEN Center for Emergent Matter Science)

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The quantum anomalous Hall effect (QAHE) is one of the hallmark phenomena arising from the non-trivial topology of the band structure of magnetic topological insulators. The Hall resistance quantizes to the quantum resistance h/e2 and the longitudinal resistance vanishes even at the zero magnetic field. We synthesized and studied heterostructure thin films of magnetic topological insulators where the magnetic element Cr was doped only in the vicinity of the topological surface states. The heterostructure allowed us to confirm that the Hall resistance is quantized to h/e2 within an uncertainty of ten parts per billion [1]. The quantization of the surface Hall conductivity was also confirmed in a sample with the Corbino disk geometry where there is no edge channel transport [2]. Recent progress in the transport properties of magnetic topological insulators will be discussed.

[1] Y. Okazaki, T. Oe, M. Kawamura, R. Yoshimi, S. Nakamura, S. Takada, M. Mogi, K. S. Takahashi, A. Tsukazaki, M. Kawasaki, Y. Tokura, N. –H. Kaneko, “Quantum anomalous Hall effect with a permanent magnet defines a quantum resistance standard”, Nature Phys. 18, 25 (2022).

[2] M. Kawamura, M. Mogi, R. Yoshimi, T. Morimoto, K. S. Takahashi, A. Tsukazaki, N. Nagaosa, M. Kawasaki, and Y. Tokura, “Laughlin charge pumping in a quantum anomalous Hall insulator”, Nature Phys. 19, 333 (2023)

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