Eur. Phys. J. B 4, 45-53 (1998)
https://doi.org/10.1007/s100510050349

Hall effect plateaus and giant Shubnikov-de Haas oscillations in (Bi_0.25Sb_0.75)₂Te₃ layered single crystals near the quantum limit

¹ Institut für Festkoerper- und Werkstofforschung Dresden, Postfach, 01171 Dresden, Germany
² Fakultät für Physik, Universität Bielefeld, Universitaetsstr. 25, 33615 Bielefeld, Germany
³ FB Physik, Martin-Luther-Universität Halle-Wittenberg, Hoher Weg 7, 06120 Halle/Saale, Germany

Received: 12 September 1997
Revised: 8 January 1998
Accepted: 22 January 1998
Published online: 15 July 1998

Abstract

On bulk layered single crystals (Bi_0.25Sb_0.75)₂Te₃ with a hole concentration 3.6X10¹⁹cm^-3 and a mobility µ=3.7X10³cm²/Vs magnetoresistance and Hall effect investigations were performed in the temperature range T = 1.4 K ... 20 K in magnetic fields up to 18 T. For the magnetic field perpendicular to the layered structure giant Shubnikov-de Haas oscillations are measured; the positions of the maxima are triplets in the reciprocally scaled magnetic field. From the damping of the amplitudes with increasing temperature the cyclotron mass m_c=0.12m₀ is evaluated. Correlated with the SdH oscillations doublets of Hall effect plateaus (or kinks in low fields) are found. The weak well known Shubnikov-de Haas oscillations from the generally accepted multivallied highest valence band can be detected as a modulation on the giant oscillation. The high anisotropy of the SdH oscillations and their triplet structure in connection with the layered crystal structure lead us to suggest that the effects are caused by hole carrier pairing (mediated by the bipolaron mechanism) in quasi 2D sheets parallel to the crystal layer stacks. The measured Hall plateau resistances coincide with the quantum Hall effect values considering the number of layer stacks and the valley degeneracy of the 3D hole carrier reservoir. The ratio of spin splitting to Landau (cyclotron) splitting is observed to be S=1±0.25.