Curvature induced out-of-plane spin accumulation in Rashba quantum waveguides

Siu, Zhuo Bin; Jalil, M. B. A.; Tan, Seng Ghee

doi:10.1063/1.4986485

Cited by 5 publications

(5 citation statements)

References 43 publications

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“…In contrast the spin polarization direction of a thin film eigenstate rotates along with the normal direction around the circumference of the tube and has an out-of-plane component. This out-of-plane component can be interpreted as the spin polarization resulting from the effective magnetization due to the curvature of the film surface generating the required torque to rotate the spin polarization around the tube circumference19.…”

Section: Resultsmentioning

confidence: 99%

Effective Hamiltonian for surface states of topological insulator nanotubes

Siu¹,

Tan²,

Jalil³

2017

Sci Rep

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In this work we derive an effective Hamiltonian for the surface states of a hollow topological insulator (TI) nanotube with finite width walls. Unlike a solid TI cylinder, a TI nanotube possesses both an inner as well as outer surface on which the states localized at each surface are coupled together. The curvature along the circumference of the nanotube leads to a spatial variation of the spin orbit interaction field experienced by the charge carriers as well as an asymmetry between the inner and outer surfaces of the nanotube. Both of these features result in terms in the effective Hamiltonian for a TI nanotube absent in that of a flat TI thin film of the same thickness. We calculate the numerical values of the parameters for a Bi2Se3 nanotube as a function of the inner and outer radius, and show that the differing relative magnitudes between the parameters result in qualitatively differing behaviour for the eigenstates of tubes of different dimensions.

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Section: Resultsmentioning

confidence: 99%

Effective Hamiltonian for surface states of topological insulator nanotubes

Siu¹,

Tan²,

Jalil³

2017

Sci Rep

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Section: Introductionmentioning

confidence: 99%

Higher Chern number states in curved periodic nanowires

Siu¹,

Tan²,

Jalil³

2022

Nanotechnology

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The coupling between the spin and momentum degrees of freedom due to spin-orbit interactions (SOI) suggests that the strength of the latter can be modified by controlling the motion of the charge carriers. In this paper, we investigate how the effective SOI can be modulated by constraining the motion of charge carriers to curved waveguides thereby introducing real-space geometric curvature in their motion. The change in the SOI can in turn induce topological phase transitions in the system. Specifically, we study how the introduction of periodic sinusoidal curvature in nanowires with intrinsic SOC can induce the onset of mid-gap topologically protected edge states, which can be characterized by a topological invariant or Chern number. The Chern number corresponds to the number of discrete charges that would be pumped across the length of the nanowire when the phase of a sliding gate potential relative to that of the sinusoidal curvature is varied adiabatically over a complete period. In addition, coupling to an external magnetization can be utilized as an experimental knob to modify the Chern number by displacing the energies of the curvature-induced bands relative to one another. The magnetization can be tuned to achieve large discrete jumps in the number of pump charges per phase period.

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“…In particular, a Brillouin zone can be defined and a miniband structure formed over the resulting superlattice when the curvature is periodic [12][13][14][15][16]. With the introduction of SOI, the change in the direction of motion of the charge carriers as they move on a periodically curved waveguide lying on a flat surface can, for example, induce a finite out-of-plane spin accumulation even when the SOI field is completely in-plane [17]. The important role that SOI has historically played [18,19] in the study of topologically non-trivial states in condensed matter and the fact that topological invariants are quantities defined over a Brillouin zone [20,21] suggest that the introduction of a periodic curvature can induce topological phase transitions in an otherwise topologically trivial SOI system [22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Higher Chern Number States in Curved Periodic Nanowires

Siu,

Tan,

Jalil

2021

Preprint

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The coupling between the spin and momentum degrees of freedom due to spin-orbit interactions (SOI) suggests that the strength of the latter can be modified by controlling the motion of the charge carriers. In this paper, we investigate how the effective SOI can be modulated by constraining the motion of charge carriers to curved waveguides thereby introducing real-space geometric curvature in their motion. The change in the SOI can in turn induce topological phase transitions in the system. Specifically, we study how the introduction of periodic sinusoidal curvature in nanowires with intrinsic SOC can induce the onset of mid-gap topologically protected edge states, which can be characterized by a topological invariant or Chern number. The Chern number corresponds to the number of discrete charges that would be pumped across the length of the nanowire when the phase of a sliding gate potential relative to that of the sinusoidal curvature is varied adiabatically over a complete period. In addition, coupling to an external magnetization can be utilized as an experimental knob to modify the Chern number by changing the ordering of the nanowire energy bands. The magnetization can be tuned to achieve large discrete jumps in the number of pump charges per phase period.

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Curvature induced out-of-plane spin accumulation in Rashba quantum waveguides

Cited by 5 publications

References 43 publications

Effective Hamiltonian for surface states of topological insulator nanotubes

Effective Hamiltonian for surface states of topological insulator nanotubes

Higher Chern number states in curved periodic nanowires

Higher Chern Number States in Curved Periodic Nanowires

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