Prolonged duration of nonequilibrated Dirac fermions in neutral topological insulators

Scientific Reports
K SumidaA Kimura

Abstract

Topological insulators (TIs) possess spin-polarized Dirac fermions on their surface but their unique properties are often masked by residual carriers in the bulk. Recently, (Sb1-x Bi x )2Te3 was introduced as a non-metallic TI whose carrier type can be tuned from n to p across the charge neutrality point. By using time- and angle-resolved photoemission spectroscopy, we investigate the ultrafast carrier dynamics in the series of (Sb1-x Bi x )2Te3. The Dirac electronic recovery of ∼10 ps at most in the bulk-metallic regime elongated to >400 ps when the charge neutrality point was approached. The prolonged nonequilibration is attributed to the closeness of the Fermi level to the Dirac point and to the high insulation of the bulk. We also discuss the feasibility of observing excitonic instability of (Sb1-x Bi x )2Te3.

References

Mar 16, 2007·Physical Review Letters·Liang FuE J Mele
Mar 12, 2010·Nature·Joel E Moore
Dec 8, 2011·Nature Communications·Jinsong ZhangYayu Wang
Jul 26, 2014·Physical Review Letters·Matthew BrahlekSeongshik Oh
Jan 3, 2015·The Review of Scientific Instruments·Y IshidaS Shin
Sep 26, 2015·Physical Review Letters·Madhab NeupaneM Zahid Hasan

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Citations

May 18, 2018·Journal of Physics. Condensed Matter : an Institute of Physics Journal·Ryota AkiyamaShuji Hasegawa
Jun 15, 2018·Scientific Reports·Munisa NurmamatAkio Kimura
Dec 18, 2019·Nature Communications·Yasen HouDong Yu
Oct 27, 2020·Journal of Physics. Condensed Matter : an Institute of Physics Journal·David O'Brien, Vadym Apalkov

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