Non-equilibrium Band Broadening, Gap Renormalization and Band Inversion in Black Phosphorus

Hedayat, Hamoon; Ceraso, A.; Soavi, Giancarlo; Akhavan, Shahab; Cadore, Alisson R.; Dallera, C.; Cerullo, Giulio; Ferrari, Andrea C.; Carpene, E.

doi:10.48550/arxiv.2007.09754

Cited by 2 publications

(2 citation statements)

References 55 publications

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“…This has motivated out-of-equilibrium experiments on TIs. In particular, time-and angle-resolved photoemission spectroscopy (trARPES) provides valuable information on electron in-teractions [23,[25][26][27][28][29][30] as it gives access to the time evolution of excited carriers in the reciprocal space [31][32][33]. However, detecting the spin degrees of freedom requires a more sophisticated method [18,34,35].…”

Section: Introductionmentioning

confidence: 99%

Ultrafast evolution of bulk, surface and surface resonance states in photoexcited $$\hbox {Bi}_{2}\hbox {Te}_{3}$$

Hedayat¹,

Bugini²,

Yi³

et al. 2021

Sci Rep

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We use circular dichroism (CD) in time- and angle-resolved photoemission spectroscopy (trARPES) to measure the femtosecond charge dynamics in the topological insulator (TI) $$\hbox {Bi}_{2}\hbox {Te}_{3}$$ Bi 2 Te 3 . We detect clear CD signatures from topological surface states (TSS) and surface resonance (SR) states. In time-resolved measurements, independently from the pump polarization or intensity, the CD shows a dynamics which provides access to the unexplored electronic evolution in unoccupied states of $$\hbox {Bi}_{2}\hbox {Te}_{3}$$ Bi 2 Te 3 . In particular, we are able to disentangle the unpolarized electron dynamics in the bulk states from the spin-textured TSS and SR states on the femtosecond timescale. Our study demonstrates that photoexcitation mainly involves the bulk states and is followed by sub-picosecond transport to the surface. This provides essential details on intra- and interband scattering in the relaxation process of TSS and SR states. Our results reveal the significant role of SRs in the subtle ultrafast interaction between bulk and surface states of TIs.

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Section: Introductionmentioning

confidence: 99%

Ultrafast evolution of bulk, surface and surface resonance states in photoexcited $$\hbox {Bi}_{2}\hbox {Te}_{3}$$

Hedayat¹,

Bugini²,

Yi³

et al. 2021

Sci Rep

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show abstract

“…Figure 2a shows the temperature dependent oscillatory response of TRR below the CDW phase transition temperature, T CDW = 202 K. We removed the incoherent electronic part (first term in Eq 2) by subtracting an exponential function from TRR measurements. We calculate the photo-generated carrier density through n e = F (1 − R)α/hν, where F , R and α denote to pump fluence, the reflectivity and penetration depth in 1T -TiSe 2 for the photon energy of the pump [55]. We estimate R = 0.6 and α = 15 nm from Refs.…”

Section: Combined Ultrafast Techniquesmentioning

confidence: 99%

Investigation of the Non-equilibrium State of Strongly Correlated Materials by Complementary Ultrafast Spectroscopy Techniques

Hedayat,

Sayers,

Ceraso

et al. 2020

Preprint

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Photoinduced non-thermal phase transitions are new paradigms of exotic non-equilibrium physics of strongly correlated materials. An ultrashort optical pulse can drive the system to a new order through complex microscopic interactions that do not occur in the equilibrium state. Ultrafast spectroscopies are unique tools to reveal the underlying mechanisms of such transitions which lead to transient phases of matter. Yet, their individual specificities often do not provide an exhaustive picture of the physical problem. One effective solution to enhance their performance is the integration of different ultrafast techniques. This provides an opportunity to simultaneously probe physical phenomena from different perspectives whilst maintaining the same experimental conditions. In this context, we performed complementary experiments by combining time-resolved reflectivity and time and angle-resolved photoemission spectroscopy. We demonstrated the advantage of this combined approach by investigating the complex charge density wave (CDW) phase in 1T -TiSe2. Specifically, we show the key role of lattice degrees of freedom to establish and stabilize the CDW in this material.

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Non-equilibrium Band Broadening, Gap Renormalization and Band Inversion in Black Phosphorus

Cited by 2 publications

References 55 publications

Ultrafast evolution of bulk, surface and surface resonance states in photoexcited $$\hbox {Bi}_{2}\hbox {Te}_{3}$$

Ultrafast evolution of bulk, surface and surface resonance states in photoexcited $$\hbox {Bi}_{2}\hbox {Te}_{3}$$

Investigation of the Non-equilibrium State of Strongly Correlated Materials by Complementary Ultrafast Spectroscopy Techniques

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