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Quantum capacitance of an ultrathin topological insulator film in a magnetic field.

Tahir M, Sabeeh K, Schwingenschlögl U - Sci Rep (2013)

Bottom Line: 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.

View Article: PubMed Central - PubMed

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.


Quantum capacitance as a function of the Fermi energy for different tilt angles of the magnetic field: 0° (dashed lines), 40° (red solid lines), 70° (blue solid lines), and 80° (black solid lines).We use B = 7 T and Γ = 25 K.
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f4: Quantum capacitance as a function of the Fermi energy for different tilt angles of the magnetic field: 0° (dashed lines), 40° (red solid lines), 70° (blue solid lines), and 80° (black solid lines).We use B = 7 T and Γ = 25 K.

Mentions: Following the same procedure as before, we employ the energy spectrum to compute the quantum capacitance, which is plotted in Fig. 4 as a function of the Fermi energy (gate voltage) for different tilt angles. We focus on the broadening of the LLs and the corresponding effects on the SdH oscillations. We fix B = 7 T. The SdH oscillations are suppressed as we increase the tilt angle, since we are decreasing the perpendicular component of the magnetic field. For θ → 90°, when the magnetic field is almost completely aligned with the film, the SdH oscillations are washed out. The broadening of the LLs generally depends on the magnetic field strength, LL index, and scattering parameters. This requires a self consistent calculation, which usually is performed numerically. In order to carry out a tractable analytical calculation we choose a constant level width of Γ = 25 K. The results in Fig. 4 are consistent with the experimental Fig. 4 in Ref. 45.


Quantum capacitance of an ultrathin topological insulator film in a magnetic field.

Tahir M, Sabeeh K, Schwingenschlögl U - Sci Rep (2013)

Quantum capacitance as a function of the Fermi energy for different tilt angles of the magnetic field: 0° (dashed lines), 40° (red solid lines), 70° (blue solid lines), and 80° (black solid lines).We use B = 7 T and Γ = 25 K.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3569631&req=5

f4: Quantum capacitance as a function of the Fermi energy for different tilt angles of the magnetic field: 0° (dashed lines), 40° (red solid lines), 70° (blue solid lines), and 80° (black solid lines).We use B = 7 T and Γ = 25 K.
Mentions: Following the same procedure as before, we employ the energy spectrum to compute the quantum capacitance, which is plotted in Fig. 4 as a function of the Fermi energy (gate voltage) for different tilt angles. We focus on the broadening of the LLs and the corresponding effects on the SdH oscillations. We fix B = 7 T. The SdH oscillations are suppressed as we increase the tilt angle, since we are decreasing the perpendicular component of the magnetic field. For θ → 90°, when the magnetic field is almost completely aligned with the film, the SdH oscillations are washed out. The broadening of the LLs generally depends on the magnetic field strength, LL index, and scattering parameters. This requires a self consistent calculation, which usually is performed numerically. In order to carry out a tractable analytical calculation we choose a constant level width of Γ = 25 K. The results in Fig. 4 are consistent with the experimental Fig. 4 in Ref. 45.

Bottom Line: 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.

View Article: PubMed Central - PubMed

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.