We image the unoccupied band structure as it evolves following a circularly polarized optical excitation and observe an asymmetric electron population in momentum space, which is the spectroscopic signature of a photocurrent.

Soifer, H. et al. Indeed, both SHG and photocurrent are adept at isolating the surface states response of a three-dimension topological insulator from that of the bulk because the latter vanishes by virtue of inversion symmetry.However, this elegant approach is inept for nonmagnetic Weyl semimetals where inversion . Excitons are spin integer particles that are predicted to condense into a coherent quantum state at sufficiently low temperature. @article{PhysRevLett.122.167401, title = {Band-Resolved Imaging of Photocurrent in a Topological Insulator}, author = {Soifer, H. and Gauthier, A. and Kemper, A. F . 2017. 122: 167401 Shen ZX, Sobota J. In this work, Ag@Bi 2 Se 3 nanoplatelets were synthesized on Al 2 O 3 (100) substrates in a two-step process of thermal evaporation and magnetron sputtering. The observed features become enhanced in a range of mid-infrared frequencies where . Distinguishing bulk and surface electron-phonon coupling in the topological insulator Bi 2 Se 3 using time-resolved photoemission spectroscopy. H. Soifer et al. With the aid of a microscopic . Phys Rev Lett, 122(16):167401, 01 Apr 2019 Cited by: 1 article | PMID: 31075004 "Band resolved imaging of photocurrent in a topological insulator. Shen. , 167401 (2019). We find that the generation efficiency increases as the laser polarization is changed from linear to elliptical, and it becomes maximum for circular polarization. can resolve the optical chirality[18,19] or extract the full Stokes parameters. Whereas the basic formalism [14,17-19] and first-principles calculations [15,16,20,21] have been estab-lished, recent developments in topological science have provided us with new insights into the photocurrent response. 3D Topological Insulators Three dimensional topological insulators have two-dimensional surface states that exhibit Dirac-like dispersion similar to graphene, but the spins of the quasiparticles are locked perpendicularly to the surface current. DOI: 10.1016/j.elspec.2014.01.005 Corpus ID: 118483802; Ultrafast electron dynamics in the topological insulator Bi2Se3 studied by time-resolved photoemission spectroscopy @article{Sobota2014UltrafastED, title={Ultrafast electron dynamics in the topological insulator Bi2Se3 studied by time-resolved photoemission spectroscopy}, author={Jonathan A. Sobota and Shuolong Yang and Dominik . Bi2Se3 is a topological quantum material that is used in photodetectors, owing to its narrow bandgap, conductive surface, and insulating bulk. Warth Prez Arias, Erica . DOI: 10.1016/j.elspec.2014.01.005 Corpus ID: 118483802; Ultrafast electron dynamics in the topological insulator Bi2Se3 studied by time-resolved photoemission spectroscopy @article{Sobota2014UltrafastED, title={Ultrafast electron dynamics in the topological insulator Bi2Se3 studied by time-resolved photoemission spectroscopy}, author={Jonathan A. Sobota and Shuolong Yang and Dominik . Energies are referenced to the 1stDirac point. and D. Yu, "On the Use of Photocurrent Imaging To Determine Carrier Diffusion Lengths in Nanostructured Thin-Film Field-Effect Transistors," The .

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Band-Resolved Imaging of Photocurrent in a Topological Insulator. . In this work, we show that scanning nano-photocurrent imaging is a fast and non-invasive technique for determining the twist angle of TBG with nano-scale spatial resolution. We image the unoccupied band structure as it evolves following an optical excitation and observe an asymmetric electron population in momentum space that is controlled by the light polarization. You will be redirected to the full text document in the repository in a few seconds, if not click here.click here. It is evident that at the applied bias volt- Photocurrent generation in graphene is dominated by the photothermoelectric effect. Here we report novel electric frequency doubling in the absence of BCD on a surface of the topological insulator Bi 2 Se 3 under zero magnetic field. In this work, Ag@Bi2Se3 nanoplatelets were synthesized on Al2O3(100) substrates in a two-step process of thermal evaporation and magnetron sputtering. [19] J. Kanasaki; H. Tanimura; K. Tanimura Imaging energy . photocurrents Physics & Astronomy Band Structure of Topological Insulators from Noise Measurements in Tunnel Junctions . A. Sobota, and Z.-X. - Tomas Palacios.

40. Our ARPES data clearly observed the Dirac cone in Na 3 Bi and showed that the Dirac cone is 3D/bulk in nature. ( 2017 ) Condensed-matter physics: Taking control of spin currents. A Biblioteca Virtual em Sade uma colecao de fontes de informacao cientfica e tcnica em sade organizada e armazenada em formato eletrnico nos pases da Regio Latino-Americana e do Caribe, acessveis de forma universal na Internet de modo compatvel com as bases internacionais. Electronic band structure Surface states ABSTRACT Topological insulators (TIs) with unique band structures have wide application prospects in the fields of ultrafast optical and spintronic devices.

. Nonlinear responses offer a symmetry-based approach to distinguish the surface and bulk responses. We find that the Dirac points are located very close to the Fermi level.

41. TBG can become a superconductor (1), a correlated insulator (2), or a quantum anomalous Hall insulator (3 -5).

. Band structure 66%. Band-Resolved Imaging of Photocurrent in a Topological Insulator H. Soifer, A. Gauthier, A. F. Kemper, C. R. Rotundu, S.-L. Yang, H. Xiong, D. Lu, M. Hashimoto, P. S. Kirchmann, J.

The observed phase boundaries in the same device can have a profound impact on its optoelectronic properties by locally breaking the crystal symmetry and giving rise to otherwise symmetry forbidden . A key . A detailed understanding of optical coupling to spin-orbital degrees of freedom is required for a microscopic picture of photocurrent generation in topological insulators. . Topological materials exhibit band crossings protected by global symmetries and topological invariants. X-ray diffractometer (XRD), high-resolution transmission electron microscopy (HRTEM), Raman . Our objective is to develop a new mechanism of broadband terahertz radiation by taking advantage of the chiral spin texture of a new quantum state-of-matter topological insulator. We study the microscopic origins of photocurrent generation in the topological insulator Bi_{2}Se_{3} via time- and angle-resolved photoemission spectroscopy. A., . Topological Materials and Topological Phase Transition; The seminal discovery of quantum spin Hall (QSH) effect engendered a new chapter of topological materials research in condensed matter physics and materials science, followed by the discoveries of three-dimensional topological insulator, quantum anomalous Hall insulator, topological crystalline materials, Weyl semimetals etc.

We report the observation of an anomalous nonlinear optical response of the prototypical three-dimensional topological insulator bismuth selenide through the process of high-order harmonic generation.

Xu, et al., "Topological surface states: a new type of 2D electron systems" in Topological Insulators, book chapter, edited by M. Franz and L. Molenkamp (2013) Admin Login OpenScholar .

We image the unoccupied band structure as it evolves following an optical excitation and observe an asymmetric electron population in momentum space that is controlled by the light polarization. . photocurrent response in ferroelectric materials [15,16]. To characterize the unusual electronic structures of these new . 1 Introduction. 122: 167401. The spin-polarized surface states of topological insulators (TIs) are attractive for applications in spintronics and quantum computing.

Band-resolved imaging of photocurrent in a topological . We study the microscopic ingredients to photocurrent generation in the topological insulator Bi2Se3 using time-resolved photoemission spectroscopy. at various spectral wavelengths with different spectral band-widths, while measured photocurrent ranges from pA to 100nA. lifetime and metal-insulator band offset in vanadium dioxide . "Time-resolved RIXS experiment with pulse-by-pulse parallel readout data collection using X-ray free . Photocurrent imaging of ZrTe5 in the quasi-quantized Hall regime. Learn about the people who make Yang Lab tick.

A central challenge with these materials is to reliably tune the chemical potential of their electrons with respect to the Dirac point and the bulk bands. Three-dimensional nature of the band structure of measured by high-momentum-resolution . which we subsequently image with scanning photocurrent microscopy. The U.S. Department of Energy's Office of Scientific and Technical Information Phys. The system hosting a topologically nontrivial [20] Topological insulators (TIs) are a new phase of quantum materials with topological surface states (TSS) on the sur-face. We have performed angle-resolved photoemission spectroscopy (ARPES) measurements to investigate the electronic structures of Na 3 Bi single crystals and found that it is a 3D counterpart of graphene. H Soifer, A Gauthier, AF Kemper, CR Rotundu, SL Yang . Band-resolved imaging of photocurrent in a topological insulator. Here, we show that Bi2TeI is a dual topological insulator. Remarkably, we obtain the shortest time resolution among the trARPES setups using solid-state nonlinear crystals for frequency upconversion. ACS Earth Space Chem. Band-resolved imaging of photocurrent in a topological insulator. (b) DFT calculation of the band structure. Lett.

[Submitted on 23 Dec 2017 ( v1 ), last revised 19 Mar 2018 (this version, v2)] Band resolved imaging of photocurrent in a topological insulator Hadas Soifer, Alexandre Gauthier, Alexander F. Kemper, Costel R. Rotundu, Shuolong Yang, Hongyu Xiong, Donghui Lu, Makoto Hashimoto, Patrick S. Kirchmann, Jonathan A. Sobota, Zhi-Xun Shen The topological insulators under consideration are three dimensional topological insulators of the second generation. Soifer H, Gauthier A, Kemper AF, Rotundu CR, Yang SL, Xiong H, Lu D, Hashimoto M, Kirchmann PS, Sobota JA, Shen ZX. On the Use of Photocurrent Imaging To Determine Carrier Diffusion Lengths in Nanostructured Thin-Film Field-Effect Transistors . Anomalous helicity-dependent photocurrent in the topological insulator ( Bi0.5Sb0.5 ) 2Te3 on a GaAs . (a) Sketch of the experimental geometry. Unusually long free carrier lifetime and metal-insulator band offset in vanadium dioxide . In these novel materials, the unusual bulk and surface electrons not only give rise to many exotic physical phenomena but also foster potential new technological applications. Extrinsically, symmetry can be broken by joining dissimilar materials, forming the basis for the p-n junction photodetector and solar cell [13 . photocurrent directionality in band structures where the carrier's crystal momentum is coupled to its angular mo-mentum, as in gyrotopic crystals [10,11] and topologi-cal insulator surface states [12]. The mirror symmetry of the crystal structure concurrently classifies it as a topological crystalline insulator. 10.1038/s41467-019-13711-3 . (b) Experimental setup with the coordinates used in this work.The film is illuminated at normal incidence, and the . Band-Resolved Imaging of Photocurrent in a Topological Insulator Full Record References (65) Cited by (4) Related Research Abstract We study the microscopic origins of photocurrent generation in the topological insulator Bi 2 Se 3 via time- and angle-resolved photoemission spectroscopy. To ensure that the photoelectrons are space charge free, a current versus voltage (I-V) scan was performed from low to high photocurrent conditions, pA, nA, and 100nA, see Fig. The polarity and magnitude of contact photocurrent are used to study the band alignment and graphene electrical potential near contacts, from which it is shown that there exist large-scale spatial variations in graphene electric potential. We image the unoccupied band structure as it evolves following a circularly polarized optical excitation and observe an asymmetric electron population in momentum space, which is the spectroscopic signature of a photocurrent. 2017. Topological materials exhibit band crossings protected by global symmetries and topological invariants. 2. In the past few years, the concept of topological matter has inspired considerable research in broad areas of physics. As a new class of quantum matter, topological insulators with insulating bulk and conducting surface states have attracted attention in more and more research fields other than condensed matter physics due to their intrinsic physical properties, which .

This review briefly describes the development of synthetic topological insulator materials in the application of advanced electronic devices. 122, 167401 Revealing the Coulomb interaction strength in a cuprate superconductor S.-L. Yang, J. It exhibits band inversions at two time reversal symmetry points of the bulk band, which classify it as a weak topological insulator with metallic states on its 'side' surfaces. We find that the photogalvanic current is strongly suppressed for the . X-ray diffractometer (XRD), high-resolution transmission electron microscopy (HRTEM), Raman . "Band-Resolved Imaging of Photocurrent in a Topological Insulator" H. Soifer: A. Gauthier, A. F. Kemper, C . Room-temperature high-frequency transport of Dirac fermions in epitaxially grown Sb 2 Te 3 - and Bi 2 Te 3-based topological insulators. "High-Harmonic Generation from Topological Insulators" Denitsa Baykusheva: Jian Lu, Jonathan A. Sobota . Three-dimensional (3D) topological semimetal band structures, which carry . (a) Electronic structure of magnetic topological insulator: the mass gap 2 at the Dirac point, and the effects of in-plane magnetic field above the critical value B c inducing finite in-plane portion of the dopant spin S y. In this work, PISHE of three-dimensional topological insulators Sb 2 Te 3 with a thickness of 7 and 30 quintuple layer (QL) has been investigated. The overall time resolution of 100fs is extracted from cross-correlations of pump and probe pulses. The color bar corresponds to the orbital spatial contribution from surface QL, calculated as the percentage of sum of PDOS contributed from all surface QL atoms to the total PDOS of all slab atoms. Here we report novel electric frequency doubling in the absence of BCD on a surface of the topological insulator Bi2Se3 under zero magnetic field. Three-dimensional nature of the band structure of measured by high-momentum-resolution photoemission spectroscopy. We are not allowed to display external PDFs yet. the bands measured here. . 2019;122: 167401. , , [Google Scholar] Olbrich P, Golub LE, Herrmann T, et al. The Dirac point is set as zero energy. We have observed a band structure typical of a topological kagome metal: Dirac cones at K points and flat bands at M points. CIQM . [21,22] Tetradymites are known as one of the best room-temperature thermoelectric materials for decades[23-26] and also 86. 1) Topological insulators: explore how charge and spin transport in topological insulators for spintronics and quantum computation. Spatial Resolved Edge Currents and Guide-Wave Electronic States in Graphene - Pablo Jarillo-Herrero, Leonid Levitov, Amir Yacoby. 1(a).

(a) The band structure and projected density of states (PDOS) of 3 QL Bi2 Se 3 slab. Quantum computers 66%. The dynamics of hot carriers plays a key role in these TI-based devices.

Lett. The incidence plane of light is along the mir- ror plane of the sample, see Fig. Distinguishing bulk and surface electron-phonon coupling in the topological insulator Bi(2)Se(3) using time-resolved photoemission spectroscopy. . Band-Resolved Imaging of Photocurrent in a Topological Insulator. We study the photocurrent response of topological insulator surface states to circularly polarized light for arbitrary oblique incidence. H Soifer, A Gauthier, AF Kemper, CR Rotundu, SL Yang, H Xiong, D Lu, . Physical Review Letters. Previously, photocurrent imaging of MoTe 2 has only resolved crystal axis dependent responses related to the anisotropic Fermi surface [10, 20, 21]. "Origins of electronic bands in antiferromagnetic topological insulator MnBi 2 Te 4. . Band-resolved imaging of photocurrent in a topological insulator, Phys. Hosur, P. Circular photogalvanic effect on topological insulator . @article{PhysRevLett.122.167401, title = {Band-Resolved Imaging of Photocurrent in a Topological Insulator}, author = {Soifer, H. and Gauthier, A. and Kemper, A. F . The powerful tool of angle-resolved photoemission spectroscopy (ARPES) offers high-resolution energy and momentum information of the electronic band structure in thermal equilibrium, however, fails to provide direct access to the underlying scattering channels in the electronic band structure and associated excited states. Expanding the momentum field of view in angle-resolved photoemission systems with hemispherical analyzers Gauthier, N., Sobota, J. Lett. (2019) Band-Resolved Imaging of Photocurrent in a Topological Insulator. 122, 167401 (2019) - Band-Resolved Imaging of Photocurrent in a Topological Insulator Band-Resolved Imaging of Photocurrent in a Topological Insulator Abstract We study the microscopic origins of photocurrent generation in the topological insulator Bi2Se3 via time- and angle-resolved photoemission spectroscopy. vided by band-resolved imaging of the pho tocurrent response in the topological insulator Bi 2 Se 3 , which reveals tha t the transient asymmetry due to optically excited photocurrents is lost within Phys.

M. Hasan, S.-Y. 1-6 The transition from a trivial insulator . The search for broader-band terahertz sources calls for new materials and new mechanisms. Soifer, H., et al. The photocurrent distributions are independent of electric field, indicating that photoexcited .

, 5, 12, 3281-3296 (2021) . Learn more about the research going on in the Yang Lab.

P. S. Kirchmann, J. Topological hyperbolic band insulators. Twisted bilayer graphene (TBG) is known to contain spatial variations in the twist angle. Nanosecond dynamics in intrinsic topological insulator Bi2xSbxSe3 revealed by time-resolved optical reflectivity. Time-resolved ARPES makes it possible to directly visualize the band dispersion of photoexcited solids, as well as to study its time evolution on the femtosecond time scale. Nanoscale resolved subsurface imaging by scattering . t= 0 refers to both pulses overlapping in time. : Band resolved imaging of photocurrent in a topological insulator. Rev. The recently discovered topological quantum materials (TQMs) have electronic structures that can be characterized by certain topological invariants. Manipulating the current (electric field) effects the spins (magnetic field) and vice versa.

Phys Rev . Phys. [1-5] For insulators, these band crossing are spatially localized at the crystal surface, and they form chiral edge states as in the quantum (anomalous) Hall phase or helical surface states as in the topological insulator (TI) phase. We describe the surface states within a Dirac model, including several perturbations such as hexagonal warping, nonlinear corrections to the mode velocity, and applied magnetic fields.

We anticipate that our spatially resolved photoinduced imaging scheme provides a generalizable platform for studying the non-trivial physics of gapless edge and surface states in topological materials . Rev. Physical Review Letters . H Xiong, JA Sobota, SL Yang, H Soifer, A Gauthier, MH Lu, YY Lv, . Additionally, we resolved the electron band around the point, which shows an enhanced effective mass. Rev. Soifer H, Gauthier A, Kemper AF, et al. Band-Resolved Imaging of Photocurrent in a Topological Insulator Soifer, H., Gauthier, A., . 79. Adam L Gross, Yasen Hou, Antonio Rossi, Dong Yu, and Inna M Vishik, Nanosecond dynamics in intrinsic topological insulator Bi 2-x Sb x Se 3 revealed by time-resolved optical reflectivity, Physical Review B 103 . 79: 2017: Trajectory-resolved coulomb focusing in tunnel ionization of atoms with intense, elliptically polarized laser pulses . Band-Resolved Imaging of Photocurrent in a Topological Insulator. Lett . The spin-polarized surface states of topological insulators (TIs) are attractive for applications in spintronics and quantum computing. . . Imaging Hydrodynamic Flow in Graphene Using a Scaning NV Center Magnetometer - Amir Yacoby. He continued to pursue his PhD in applied physics at Stanford University. transport of photogenerated carriers in topological insulators," Nature Communications, 10, 5723 (2019). Dispersion relations, absorption characteristics and propagation lengths of SPPs are calculated. arXiv:1712.08694 (2017) A topological insulator is a material that behaves as an insulator in . Shuolong obtained his BS in physics at Stanford University. Band-Resolved Imaging of Photocurrent in a Topological Insulator. By. Soifer H, Gauthier A, Kemper AF, et al. PMID 31075004 DOI: 10.1103/PhysRevLett.122.167401 : 0.8: 2019: . It is revealed that both of the PISHE currents of the top and bottom surface states are observed in the 7-QL and the 30-QL samples. Together they form a unique fingerprint. Photoelectrons are collected in a hemispherical analyzer along the -K direction [30]. We observe that the frequency-doubling voltage.

Further support is provided by band-resolved imaging of the photocurrent response in the topological insulator Bi 2 Se 3, which reveals that the transient asymmetry due to optically excited. We demonstrate persistent, bidirectional optical . Our work provides a microscopic understanding of how to control photocurrents in systems with spin-orbit coupling and broken inversion symmetry. We use scanning probe photocurrent imaging to resolve nanoscale variations of the Seebeck coefficient occurring at these domain walls. Fingerprint Dive into the research topics of 'Band-Resolved Imaging of Photocurrent in a Topological Insulator'. Phys Rev Lett. . The tight confinement of electromagnetic fields in the resonant nanostructure enhances the photoexcitation of spin-polarized surface states of topological insulator Bi 1.5 Sb 0.5 Te 1.8 Se 1.2, leading to an 11-fold increase of the circular photogalvanic effect and a previously unobserved photocurrent dichroism ( circ = 0.87) at room temperature. . The ability to optically write and erase mesoscopic electronic structures in a TI may aid in the investigation of the unique properties of . Before coming to the Pritzker School of Molecular Engineering at the University of Chicago as assistant professor of molecular engineering in 2018, Prof. Yang was a Kavli postdoctoral fellow at Cornell University, working at the interface between condensed .

Rev. A. Sobota, Y. Learn more about the instruments we use everyday here.. Physical Review B 95 (19), 195119. , 2017. Band-resolved imaging of photocurrent in a topological insulator. resolved photoemission signal F Boschini et al-Band-Resolved Imaging of Photocurrent in a Topological Insulator H. Soifer et al-Observation of chiral surface excitons in a topological insulator Bi2Se3 H.-H. Kung et al-This content was downloaded from IP address 207.46.13.222 on 23/04/2020 at 22:17 Here by using photocurrent imaging we report experimental evidence of formation and efficient transport of non-equilibrium excitons in Bi 2-x Sb x Se 3 nanoribbons. It provides a first-time all-in-one solution to achieve an energy resolution of < 4 meV, a time resolution of < 35 fs, and a spatial resolution of 10 m in photoemission spectroscopy. 2020. Bi 2 Se 3 is a topological quantum material that is used in photodetectors, owing to its narrow bandgap, conductive surface, and insulating bulk. Schematic energy dispersion and transport properties. (2021) Charge Transport in Single-Crystalline GaAs Nanobars: Impact of Band Bending Revealed by Terahertz Spectroscopy.

In particular, photonic artificial microstructures like photonic crystals and metamaterials provide a unique platform to investigate topologically non-trivial physics in spin-1 electromagnetic fields.