Quantum capacitance of an ultrathin topological insulator film in a magnetic field.
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We present a theoretical study of the quantum magnetocapacitance of an ultrathin topological insulator film in an external magnetic field.This leads to a change in the character of the magnetocapacitance at the charge neutrality point.In addition, we address the crossover from perpendicular to parallel magnetic field and find consistency with recent experimental data.
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Affiliation: PSE Division , KAUST, Thuwal 23955-6900, Kingdom of Saudi Arabia.
ABSTRACT
We present a theoretical study of the quantum magnetocapacitance of an ultrathin topological insulator film in an external magnetic field. The study is undertaken to investigate the interplay of the Zeeman interaction with the hybridization between the upper and lower surfaces of the thin film. Determining the density of states, we find that the electron-hole symmetry is broken when the Zeeman and hybridization energies are varied relative to each other. This leads to a change in the character of the magnetocapacitance at the charge neutrality point. We further show that in the presence of both Zeeman interaction and hybridization the magnetocapacitance exhibits beating at low and splitting of the Shubnikov de Haas oscillations at high perpendicular magnetic field. In addition, we address the crossover from perpendicular to parallel magnetic field and find consistency with recent experimental data. No MeSH data available. |
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Mentions: The magnetocapacitance CQ is plotted in Figs. 1 and 2 as a function of the Fermi energy (i.e., of the gate voltage). The following parameters are employed2230414243: g = 60, B = 3 T, Δz = 5 meV, and Δh = 3 meV. To obtain analytical results, we choose a constant level width of Γ = 0.3 meV. We are interested in changes of the character at εF = 0 on variation of the Zeeman interaction and hybridization relative to each other. It must be noted that the n = 0 LL here plays the most important role. Figure 1 shows that CQ is zero at εF = 0. This occurs because the n = 0 LL splits only when the hybridization does not vanish. The n = 0 LL splits into one electron and one hole level, which reflects a metal to insulator transition caused by the hybridization (for Δz = 0). The states are electron-hole symmetric at this stage. CQ can be tuned from a minimum to a maximum when the Zeeman energy is increased by changing the external magnetic field. For Δz > Δh both n = 0 sublevels are located in the hole region, which breaks the electron-hole symmetry, see Fig. 2, and represents the trivial to non-trivial topological insulator phase transition. To observe the splitting, the broadening of the LLs must be less than the hybridization energy. We note that not only the n = 0 LL but all LLs are split into two sublevels. |
View Article: PubMed Central - PubMed
Affiliation: PSE Division , KAUST, Thuwal 23955-6900, Kingdom of Saudi Arabia.
No MeSH data available.