Laser-induced persistent photovoltage on the surface of a ternary topological insulator at room temperature

Abstract

Using time- and angle-resolved photoemission, we investigate the ultrafast response of excited electrons in the ternary topological insulator (Bi${}_{1x}$Sb${}_x$)${}_2$Te${}_3$ to fs-infrared pulses. We demonstrate that at the critical concentration $x$=0.55, where the system becomes bulk insulating, a surface voltage can be driven at room temperature through the topological surface state solely by optical means. We further show that such a photovoltage persists over a time scale that exceeds $\sim$6 $\mu$s, i.e, much longer than the characteristic relaxation times of bulk states. We attribute the origin of the photovoltage to a laser-induced band-bending effect which emerges near the surface region on ultrafast time scales. The photovoltage is also accompanied by a remarkable increase in the relaxation times of excited states as compared to undoped topological insulators. Our findings are relevant in the context of applications of topological surface states in future optical devices.

arXiv comment5 pages, 4 figures

References in corpus (28)

• Topological Insulators
• Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator
• First observation of Spin-Momentum Helical Locking in Bi2Se3 and Bi2Te3, demonstration of Topological-Order at 300K and a realization of topological-transport-regime
• Topological Insulator Materials
• Observation of Floquet-Bloch states on the surface of a topological insulator
• First direct observation of Spin-textures in Topological Insulators : Spin-resolved ARPES as a probe of topological quantum spin Hall effect and Berry's phase
• Spintronics and Pseudospintronics in Graphene and Topological Insulators
• Topological Surface States Protected From Backscattering by Chiral Spin Texture
• Super-Diffusive Spin-Transport as a Mechanism of Ultrafast Demagnetization
• Hexagonal Warping Effects in the Surface States of Topological Insulator Bi${}_2$Te${}_3$
• Large bulk resistivity and surface quantum oscillations in the topological insulator Bi2Te2Se
• Band structure engineering in (Bi1-xSbx)2Te3 ternary topological insulators
• Spin Polarization and Transport of Surface States in the Topological Insulators Bi2Se3 and Bi2Te3 from First Principles
• Ambipolar Field Effect in Topological Insulator Nanoplates of (BixSb1-x)2Te3
• Ultrafast Optical Excitation of a Persistent Surface-State Population in the Topological Insulator Bi2Se3
• Optimizing the Bi_(2-x)Sb_(x)Te_(3-y)Se_(y) solid solutions to approach the intrinsic topological insulator regime
• Electronic Structure of the Topological Insulator Bi2Se3 Using Angle-Resolved Photoemission Spectroscopy: Evidence for a Nearly Full Surface Spin Polarization
• Direct Measurement of the Out-of-Plane Spin Texture in the Dirac Cone Surface State of a Topological Insulator
• Quantum Hall Effect on Top and Bottom Surface States of Topological Insulator (Bi1-xSbx)2Te3 Films
• Sn-doped Bi1.1Sb0.9Te2S, a bulk topological insulator with ideal properties
• Widespread spin polarization effects in photoemission from topological insulators
• Gigantic surface life-time of an intrinsic topological insulator revealed via time-resolved (pump-probe) ARPES
• Photoemission of Bi${}_2$Se${}_3$ with Circularly Polarized Light: Probe of Spin Polarization or Means for Spin Manipulation?
• Ultrafast spin polarization control of Dirac fermions in topological insulators
• Generation of Transient Photocurrents in the Topological Surface State of Sb${}_2$Te${}_3$ by Direct Optical Excitation with Mid-Infrared Pulses
• Ultrafast and gigantic spin injection in semiconductors
• Sub-picosecond spin dynamics of excited states in the topological insulator Bi${}_2$Te${}_3$
• Realization of bulk insulating property and carrier manipulation in reversible spin current regime of the ideal topological insulator TlBiSe2

Cited by in corpus (5)

• Time- and Angle-Resolved Photoemission Studies of Quantum Materials
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• Impact of ultrafast transport on the high-energy states of a photoexcited topological insulator
• Role of matrix elements in the time-resolved photoemission signal
• Spectroscopic evidence of intra-unit-cell charge redistribution in charge-neutral magnetic topological insulator Sb-doped MnBi6Te10