Magnetotransport property of negative band gap HgCdTe bulk material

Abstract

In recent years, spintronic devices have attracted more and more attention because of their good characteristics. The spin-orbit coupling of HgCdTe is one of the most important parts in the study of narrow gap semiconductors. The magneotransport properties of the Hg0.9Cd0.1Te bulk material with an inverted band structure have been hardly reported so far. The spin-orbit coupling strength of HgCdTe is closely related to the band gap. The strength of the spin-orbit coupling increases with the width of the band gap decreasing. Thus, Hg0.9Cd0.1Te should have strong spin-orbit coupling. Meanwhile it should be one of the most suitable materials to fabricate spintronic devices. The main propose of our experiments is to prove this inference. Inside the sample, Rashba spin-orbit interaction (SOI) strongly influences the spin-splitting due to the lack of structural inversion symmetry. In other words, Rashba SOI is the main part of the zero field spin splitting △0. The band structure of Hg1-xCdxTe can be precisely tuned by changing the composition of Cd which keeps an inverted band order when 0 x Γ8 band lying below the Γ6 band (or equivalently a positive band gap) when x0.165. In this paper, the p-type HgCdTe bulk material with Cd component of 0.1 is grown by single crystal. Anodic oxidation is used to induce an inversion layer on the HgCdTe bulk, and indium is used to facilitate Ohmic contacts. The magnetoresistance is measured in the van der Pauw configuration, and the magnetic field is applied perpendicularly to the film. All measurements are carried out in an Oxford Instruments He cryogenic system. At 1.5 K and zero gate voltage, the carrier density n is 1.3×1016 m-2. Clear Shubnikov-de Haas (SdH) oscillation in ρxx and quantum Hall plateaus of Rxy are observed in the Hg0.9Cd0.1Te bulk material with an inverted band structure is investigated in magnetotransport experiment. This indicates that our sample is a good transistor. Fast Fourier transformation is used to deduce the zero-field spin-splitting △0 which is about 26.55 meV. By studying the beating patterns in SdH oscillations we find that the effective g-factor is about-11.54. Both the large zero field spin splitting and the negative effective g-factor suggest that Hg0.9Cd0.1Te has really strong spin-orbit coupling. The investigation of SOI in Hg0.9Cd0.1Te can increase our knowledge of Hg-based narrow-gap semiconductors and benefit the field of spintronics.