Abstract
Aharonov–Bohm conductance oscillations emerge as a result of gapless surface states in topological insulator nanowires. This quantum interference accompanies a change in the number of transverse one-dimensional modes in transport, and the density of states of such nanowires is also expected to show Aharonov–Bohm oscillations. Here, we demonstrate a novel characterization of topological phase in Bi2Se3 nanowire via nanomechanical resonance measurements. The nanowire is configured as an electromechanical resonator such that its mechanical vibration is associated with its quantum capacitance. In this way, the number of one-dimensional transverse modes is reflected in the resonant frequency, thereby revealing Aharonov–Bohm oscillations. Simultaneous measurements of DC conductance and mechanical resonant frequency shifts show the expected oscillations, and our model based on the gapless Dirac fermion with impurity scattering explains the observed quantum oscillations successfully. Our results suggest that the nanomechanical technique would be applicable to a variety of Dirac materials.
Highlights
Aharonov–Bohm conductance oscillations emerge as a result of gapless surface states in topological insulator nanowires
The characterization of various topological phases of matter is at the cutting edge of experimental condensed matter physics
We employ nanomechanical resonance measurements to characterize the topological phase of a Bi2Se3 nanowire through AB-type oscillation
Summary
Aharonov–Bohm conductance oscillations emerge as a result of gapless surface states in topological insulator nanowires This quantum interference accompanies a change in the number of transverse one-dimensional modes in transport, and the density of states of such nanowires is expected to show Aharonov–Bohm oscillations. The nanowire is configured as an electromechanical resonator such that its mechanical vibration is associated with its quantum capacitance In this way, the number of one-dimensional transverse modes is reflected in the resonant frequency, thereby revealing Aharonov–Bohm oscillations. The resonant frequency of nanomechanical motion carries the signal that shows AB oscillations correlated to the conductance modulation, suggesting the application of our novel sensing scheme to studies of various topological materials with Dirac electronic structures. Detection of the quantum capacitance effects from surface-state DOS is facilitated by the small effective capacitances[20] and high quality factors[21,22] of nanomechanical resonators, and as such the present technique could be extended to study diverse quantum materials at nanoscale
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