Bidirectional surface photovoltage on a topological insulator

Yoshikawa, Tomohiro; Sumida, Kazuki; Ishida, Y.; Chen, J.; Nurmamat, Munisa; Akiba, Kazuto; Miyake, Atsushi; Tokunaga, Masashi; Кох, К. А.; Tereshchenko, O. E.; Shin, Shik; Kimura, Akio

doi:10.1103/physrevb.100.165311

Cited by 15 publications

(13 citation statements)

References 40 publications

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“…In addition, very different relaxation times of the excited states between both samples are found (Extended Data 7e). Only if the Fermi level is situated inside the bulk band gap, we observe a slow (≥ 4 µs) relaxation, similar to that observed in other topological insulators [13][14][15][16][17][18] . Our accompanying transport study on the same material allows us to relate this "more-than-4 µs-long" relaxation to an ultraslow "morethan-hour-long" relaxation.…”

Section: Resultssupporting

confidence: 85%

“…This leads to a significant boost of the surface conduction, which can be adjusted by the amplitude of the external excitation. We find striking similarities between our results and previous spectroscopic studies [12][13][14][15][16][17][18] and propose a mechanism that should hold for any topological insulator. This new understanding opens new routes to further fundamental studies and may pave the way towards applications of robust bulk 3D topological insulators.…”

supporting

confidence: 88%

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Boosting the surface conduction in a topological insulator

Taupin

Eguchi

Budnowski

et al. 2021

Preprint

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The protected surface conduction of topological insulators is in high demand for the next generation of electronic devices. What is needed to move forward are robust settings where topological surface currents can be controlled by simple means, ideally by the application of external stimuli. Surprisingly, this direction is only little explored and the role of topological states in such processes has remained obscure. In this work we demonstrate that we can boost the surface conduction of a topological insulator by light and/or electric field. This happens in a fully controlled way, and the additional Dirac carriers exhibit ultra-long live times. We provide a comprehensive understanding—carriers injection from the bulk to the surface states across an intrinsic Schottky barrier—and expect this mechanism to be at play in a broad range of materials and experimental settings.

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Section: Resultssupporting

confidence: 85%

supporting

confidence: 88%

Boosting the surface conduction in a topological insulator

Taupin

Eguchi

Budnowski

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…In addition, very different relaxation times of the excited states between both samples are found (Extended Data 6e). Only if the Fermi level is situated inside the bulk band gap, we observe a slow (≥ 4 µs) relaxation, similar to that observed in other topological insulators [11][12][13][14][15][16] . Our accompanying transport study on the same material allows us to relate this "more-than-4 µs-long" relaxation to an ultraslow "morethan-hour-long" relaxation.…”

supporting

confidence: 85%

Switching on surface conduction in a topological insulator

Taupin¹,

Eguchi²,

Budnowski³

et al. 2020

Preprint

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The protected surface conductivity of topological insulators, carried by ultra-relativistic Dirac fermions, is in high demand for the next generation of electronic devices. Progress in the unambiguous identification of this surface contribution and, in a second step, its control are needed to move forward. Here we demonstrate both, with a combined transport and spectroscopy study of highquality single crystals and mesoscopic devices of the topological insulator TlBiSe 2−δ 1-5 . We show how various external stimuli-from thermal radiation, via low-intensity light, to high-intensity laser pumping and current driving-can boost the surface contribution, thereby making it both unambiguously detectable and potentially exploitable for applications. Once switched on, the extra surface contribution is persistent, with lifetimes of hundreds of years at low temperatures. We understand this effect in terms of the well-known concept of surface charge accumulation 6,7 via a Schottky barrier formation 8,9 , and propose that the same mechanism underlies also the slow relaxations seen with spectroscopic probes in our and other 10-16 materials, which might thus also be persistent. We expect our technique to be readily transferable to other materials and probes, thereby shedding light on unexplained slow relaxations in transport [17][18][19] and beyond.

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“…The energy shift for both SCB and SVB increases with pump fluence (light and dark blue dots in Fig.2(n)) and reaches a large value of 30 meV at the highest pump fluence, while the BCB remains almost unchanged (black dots in Fig.2(n)). Such nontrivial shift of the SS but not the BCB is in contrast to electron doping of Bi 2 Se 3 where a rigid shift is observed for both the SS and BCB,27 and is similar to the surface photovoltaic effect (SPV) reported in Bi 2 Se 3 and Bi 2 Te 2 Se [28][29][30][31]. To further quantify the gap filling, we show in Fig.2(o) the intensity ratio between the dip and the peak, and a linear dependence on the pump fluence is observed.…”

supporting

confidence: 75%

Light-Tunable Surface State and Hybridization Gap in Magnetic Topological Insulator MnBi$_8$Te$_{13}$

Zhong,

Bao,

Wang

et al. 2021

Preprint

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MnBi 8 Te 13 is an intrinsic ferromagnetic (FM) topological insulator with different complex surface terminations. Resolving the electronic structures of different termination surfaces and manipulation of the electronic state are important. Here, by using micrometer-spot time-and angle-resolved photoemission spectroscopy (µ-TrARPES), we resolve the electronic structures and reveal the ultrafast dynamics upon photoexcitation. Photo-induced filling of the surface state hybridization gap is observed for the Bi 2 Te 3 quintuple layer directly above MnBi 2 Te 4 accompanied by a nontrivial shift of the surface state, suggesting light-tunable interlayer interaction. Relaxation

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Bidirectional surface photovoltage on a topological insulator

Cited by 15 publications

References 40 publications

Boosting the surface conduction in a topological insulator

Boosting the surface conduction in a topological insulator

Switching on surface conduction in a topological insulator

Light-Tunable Surface State and Hybridization Gap in Magnetic Topological Insulator MnBi$_8$Te$_{13}$

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