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

Abstract

AbstractShubnikov 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.