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Seminarium Fizyki Politechniki Wrocławskiej

11:15 Monday, 17-10-16
PWr, bud. A1, sala 322

3D Topological Insulators based on semi-metallic HgCdTe

prof. E. M. Sheregii

Centrum Mikroelektroniki i Nanotechnologii, Uniwersytet Rzeszowski

Experimental results of the magneto-transport measurements are presented over a wide interval of temperatures for several samples of MCT (x ≈ 0.13 - 0.15) grown by MBE: A series – thin layers (thickness about 100 nm) strained, AB series– not strained thin layers and B series – thick ones with thickness about 1 μm [1]. The results obtained for sample A9 – strained thin layer on the GaAs/CdTe substrate. The Rxx(B) and Rxy(B) curves are shown for different temperatures over wide range from 0.4 K to 50 K. The well-defined quantized plateaus in Rxy with values h/(2e2) = 12.9 kΩ, accompanied by vanishing Rxx is observed at 0.4 K what explicitly indicate on the Integer Quantum Hall Effect (IQHE) and Shubnikov-de Haas (SdH) oscillations characteristic for 2D electron gas. The quantization in integer multiples of σo = e2/h is evident with the Landau filling factor ν equals to 2, 4 and 6. The Rxx(B) and Rxy(B) curves are reproducible up to 20 K and above this temperature the Integer Quantum Hall Conductivity (IQHC) is observed up to 50 K. That can be explained by conductivity on topologically protected surface states (TPSS) [2]. An amazing temperature stability of the SdH-oscillation period and amplitude is observed in the entire temperature interval of measurements up to 50 K for samples of series AB and B also. Moreover, the IQHE behavior of the Hall resistance is registered in the same temperature interval. In the case of not strained layers (series AB and B) it is assumed that the QHC on the TPSS contributes also to the conductance.

[1] G. Tomaka et al., Phys. Rev. B 93, 205419 (2016)
[2] C. Brüne et al., Phys. Rev. Lett. 106, 126803 (2011)

im. Włodzimierza Trzebiatowskiego
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