Unraveling the Dirac fermion dynamics of the bulk-insulating topological system 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Bi</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Te</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mi>Se</mml:mi></mml:mrow></mml:math>

Papalazarou, E.; Khalil, Lama; Caputo, Marco; Perfetti, L.; Nilforoushan, Niloufar; Deng, Haiming; Chen, Z.; Zhao, Shengming; Taleb‐Ibrahimi, A.; Kończykowski, M.; Hruban, A.; Wołoś, Agnieszka; Materna, A.; Krusin‐Elbaum, L.; Marsi, M.

doi:10.1103/physrevmaterials.2.104202

Cited by 26 publications

(25 citation statements)

References 49 publications

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“…The approximately linear trend in the semi-log plot implies a logarithm-like dependence of the SPV time constant with fluence. Figure 3 provides a schematic representation of a possible mechanism for the long-lived SPV in p-type Bi 2 Se 3 similar to the reported mechanism from Papalazarou et al 10 . Before pumping, the equilibrium conduction and valence band are expected to bend downwards due to surface state population and redistribution of charge from bulk to surface as seen in Fig.…”

Section: Resultssupporting

confidence: 61%

“…In this case, photoelectrons appear to be affected by a pump pulse that arrives after they have been photoemitted. Previous studies have assumed the chemical potential shift at negative delay is the continuation of the SPV decay from a previous pump pulse, leading to incorrect estimates of the lifetime of the SPV (>4 μs) in similar systems [7][8][9][10] . However, our work reveals over a larger decay range that the negative time decay process is separate from the relaxation of the SPV and therefore unrelated to the previous pulse.…”

Section: Resultsmentioning

confidence: 99%

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Manipulating long-lived topological surface photovoltage in bulk-insulating topological insulators Bi2Se3 and Bi2Te3

et al. 2020

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The appearance of topologically protected spin-momentum locked surface states in topological insulators gives rise to robust room temperature spin currents making them ideal candidates for the realization of spintronic devices. New methods are needed to access and manipulate such currents with timescales that are compatible with modern electronics. Here we reveal that an optically induced long-lived (~10 ns), spin-polarized surface state excitation in topological insulators can be easily tuned in both magnitude and duration. Time-resolved angle-resolved photoemission spectroscopy, together with a quantitative model, reveals the ideal conditions for a surface photovoltage in two different topological insulators. Our model predicts that the reported effects are an intrinsic property of topological insulators, as long as the chemical potential falls within the band gap. This work demonstrates that persistent excited topological surface states are photon-accessible and easily tuned in both magnitude and duration, merging photonics-and spintronics-based devices in the same material.npj Quantum Materials (2020) 5:16 ; https://doi.

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Section: Resultssupporting

confidence: 61%

Section: Resultsmentioning

confidence: 99%

Manipulating long-lived topological surface photovoltage in bulk-insulating topological insulators Bi2Se3 and Bi2Te3

et al. 2020

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“…the Fermi momentum k F ) and velocity (v F ) extracted from an MDC fitting procedure are summarized for all delays in figure 2(e). Such an observation requires consideration of the possible impact of photoinduced surfacephotovoltage (SPV) effects, which have been reported widely in a variety of bulk-insulating TIs [36,37,[41][42][43][44]. We note that SPV would induce a rigid band shift, instead of the polarization dependent photoemission intensity dynamics reported below and in figure 4, and would thus not affect our analysis and conclusions (see supplementary material available online at stacks.iop.org/NJP/22/023031/mmedia).…”

Section: Resultsmentioning

confidence: 90%

Role of matrix elements in the time-resolved photoemission signal

et al. 2020

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Time-and angle-resolved photoemission spectroscopy (TR-ARPES) provides access to the ultrafast evolution of electrons and many-body interactions in solid-state systems. However, the momentum-and energy-resolved transient photoemission intensity may not be unambiguously described by the intrinsic relaxation dynamics of photoexcited electrons alone. The interpretation of the time-dependent photoemission signal can be affected by the transient evolution of the electronic distribution, and both the one-electron removal spectral function as well as the photoemission matrix elements. Here we investigate the topological insulator Bi 1.1 Sb 0.9 Te 2 S to demonstrate, by means of a detailed probe-polarization dependent study, the transient contribution of matrix elements to TR-ARPES.

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“…And they then can jump down to the impurity band above the top of the BVB (path 3) or the BVB (path 4), as shown in Figure 4b. Thus, these impurity bands provide additional recombination channels, which assist the relaxation of the exited carriers 34,35 .…”

Section: Discussionmentioning

confidence: 99%

Impurity band assisted carrier relaxation in Cr doped topological insulator Bi2Se3

Zhao

Zhang

et al. 2021

Applied Physics Letters

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Topological insulators (TIs) with unique band structures have wide application prospects in the fields of ultra-fast optical and spintronic devices. The dynamics of hot carriers plays a key role in these TI based devices. In this work, using time and angle resolved photoemission spectroscopy (TR-ARPES) technique, the relaxation process of the hot carriers in Cr doped Bi2Se3 has been systematically studied, where the ferromagnetic TI is one of the key building blocks for the next generation spintronics.It is found that the electronic temperature (Te) and chemical potential (μ) decrease faster with the increase of the Cr doping concentration. Similarly, the lifetime (τ) of the excited electrons also decreases with more Cr doped into TIs. The results suggest a new mechanism of the impurity bands assisted carrier relaxation, where the impurity bands within the bulk band gap introduced by Cr doping provide significant recombination channels for the excited electrons. This work directly illustrates the dynamic process of the carriers in Cr doped Bi2Se3, which is expected to promote the applications of (Bi1-xCrx)2Se3 in ultrafast optical and spintronic devices.

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Unraveling the Dirac fermion dynamics of the bulk-insulating topological system Bi2Te2Se

Cited by 26 publications

References 49 publications

Manipulating long-lived topological surface photovoltage in bulk-insulating topological insulators Bi2Se3 and Bi2Te3

Manipulating long-lived topological surface photovoltage in bulk-insulating topological insulators Bi2Se3 and Bi2Te3

Role of matrix elements in the time-resolved photoemission signal

Impurity band assisted carrier relaxation in Cr doped topological insulator Bi2Se3

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