Anomalous Decay of Quantum Resistance Oscillations of 2D Helical Electrons in Magnetic Field

Abstract

Shubnikov de Haas resistance oscillations of highly mobile two dimensional helical electrons propagating on a conducting surface of strained HgTe 3D topological insulator are studied in magnetic fields B tilted by angle θ from the normal to the conducting layer. Strong decrease of oscillation amplitude A is observed with the tilt: $${\boldsymbol{A}}\sim {\boldsymbol{e}}{\boldsymbol{x}}{\boldsymbol{p}}(\,-\,{\boldsymbol{\xi }}/{\boldsymbol{c}}{\boldsymbol{o}}{\boldsymbol{s}}({\boldsymbol{\theta }}))$$A∼exp(−ξ/cos(θ)), where ξ is a constant. Evolution of the oscillations with temperature T shows that the parameter $${\boldsymbol{\xi }}$$ξ contains two terms: $${\boldsymbol{\xi }}={{\boldsymbol{\xi }}}_{1}+{{\boldsymbol{\xi }}}_{2}{\boldsymbol{T}}$$ξ=ξ1+ξ2T. The temperature independent term, $${{\boldsymbol{\xi }}}_{{\bf{1}}}$$ξ1, signals possible reduction of electron mean free path $${l}_{q}$$lq and/or enhancement of in-homogeneous broadening of the oscillations in magnetic field B. The temperature dependent term, $${{\boldsymbol{\xi }}}_{{\bf{2}}}{\boldsymbol{T}}$$ξ2T, indicates increase of the reciprocal velocity of 2D helical electrons: $$\delta ({v}_{F}^{-1})\sim B$$δ(vF−1)∼B suggesting modification of the electron spectrum in magnetic fields. Results are found in good agreement with proposed phenomenological model.

Distinct Quantum States in Topological Insulator Surfaces of Nanowires and Nanoribbons of Bismuth Selenide (Bi2Se3)

“…Transport studies on 3D TI nanowires and nanoribbons have shown the presence of AB oscillations, Altshuler–Aronov–Spivak (AAS) oscillations, and even small contributions of Shubnikov‐de Hass (SdH) oscillations with a period of $$\frac{{\mathrm{h}}}{{2{\mathrm{e}}}}$$. [ 16,20,27,28 ] These oscillations have also been observed in 2D materials, [ 29,30 ] and, therefore, could not be used to discriminate the nature of topological surfaces in nanoribbons and nanowires. Moreover, understanding the geometries of nanostructures and their effects on the electronic structure would enable us to manipulate the topological phases.…”