title: Surface-Facet-Dependent Phonon Deformation Potential in Individual Strained Topological Insulator Bi2Se3 Nanoribbons.
abstract: Strain is an important method to tune the properties of topological insulators. For example, compressive strain can induce superconductivity in Bi2Se3 bulk material. Topological insulator nanostructures are the superior candidates to utilize the unique surface states due to the large surface to volume ratio. Therefore, it is highly desirable to monitor the local strain effects in individual topological insulator nanostructures. Here, we report the systematical micro-Raman spectra of single strained Bi2Se3 nanoribbons with different thicknesses and different surface facets, where four optical modes are resolved in both Stokes and anti-Stokes Raman spectral lines. A striking anisotropy of the strain dependence is observed in the phonon frequency of strained Bi2Se3 nanoribbons grown along the ⟨112̅0⟩ direction. The frequencies of the in-plane Eg(2) and out-of-plane A1g(1) modes exhibit a nearly linear blue-shift against bending strain when the nanoribbon is bent along the ⟨112̅0⟩ direction with the curved {0001} surface. In this case, the phonon deformation potential of the Eg(2) phonon for 100 nm-thick Bi2Se3 nanoribbon is up to 0.94 cm(–1)/%, which is twice of that in Bi2Se3 bulk material (0.52 cm(–1)/%). Our results may be valuable for the strain modulation of individual topological insulator nanostructures.
authors.affiliation: Physikalisches Institut, Universität Stuttgart , 70550 Stuttgart, Germany.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Yan
authors.affiliation: State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University , 100871 Beijing, China.|Academy for Advanced Interdisciplinary Studies, Peking University , 100871 Beijing, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Zhou
authors.affiliation: State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University , 100871 Beijing, China.
authors.forename: Han
authors.initials: H
authors.lastname: Jin
authors.affiliation: State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University , 100871 Beijing, China.
authors.forename: Cai-Zhen
authors.initials: CZ
authors.lastname: Li
authors.affiliation: EMAT (Electron Microscopy for Materials Science), University of Antwerp , Groenenborgerlaan 171, B-2020 Antwerp, Belgium.
authors.forename: Xiaoxing
authors.initials: X
authors.lastname: Ke
authors.affiliation: EMAT (Electron Microscopy for Materials Science), University of Antwerp , Groenenborgerlaan 171, B-2020 Antwerp, Belgium.
authors.forename: Gustaaf
authors.initials: G
authors.lastname: Van Tendeloo
authors.affiliation: State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University , 100871 Beijing, China.|Academy for Advanced Interdisciplinary Studies, Peking University , 100871 Beijing, China.|Collaborative Innovation Center of Quantum Matter , Beijing, China.
authors.forename: Kaihui
authors.initials: K
authors.lastname: Liu
authors.affiliation: State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University , 100871 Beijing, China.|Academy for Advanced Interdisciplinary Studies, Peking University , 100871 Beijing, China.|Collaborative Innovation Center of Quantum Matter , Beijing, China.
authors.forename: Dapeng
authors.initials: D
authors.lastname: Yu
authors.affiliation: Physikalisches Institut, Universität Stuttgart , 70550 Stuttgart, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Dressel
authors.affiliation: State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University , 100871 Beijing, China.|Collaborative Innovation Center of Quantum Matter , Beijing, China.
authors.forename: Zhi-Min
authors.initials: ZM
authors.lastname: Liao
keywords: Bi2Se3 nanoribbon; Raman spectroscopy; phonon confinement effect; strain; topological insulator