Jonathan A. Sobota
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View article: Reconstructing the wavefunction of magnetic topological insulators MnBi2Te4 and MnBi4Te7 using spin-resolved photoemission
Reconstructing the wavefunction of magnetic topological insulators MnBi2Te4 and MnBi4Te7 using spin-resolved photoemission Open
Despite their importance for exotic quantum effects, the surface electronic structure of magnetic topological insulators MnBi2Te4 and MnBi4Te7 remains poorly understood. Using high-efficiency spin- and angle-resolved photoemission spectros…
View article: Reexamining Circular Dichroism in Photoemission From a Topological Insulator
Reexamining Circular Dichroism in Photoemission From a Topological Insulator Open
The orbital angular momentum (OAM) of electron states is an essential ingredient for topological and quantum geometric quantities in solids. For example, Dirac surface states with helical spin- and orbital-angular momenta are a hallmark of…
View article: Analysis methodology of coherent oscillations in time- and angle-resolved photoemission spectroscopy
Analysis methodology of coherent oscillations in time- and angle-resolved photoemission spectroscopy Open
Oscillatory signals from coherently excited phonons are regularly observed in ultrafast pump–probe experiments on condensed matter samples. Electron–phonon coupling implies that coherent phonons also modulate the electronic band structure.…
View article: Screening of Polar Electron-Phonon Interactions near the Surface of the Rashba Semiconductor BiTeCl
Screening of Polar Electron-Phonon Interactions near the Surface of the Rashba Semiconductor BiTeCl Open
Understanding electron-phonon coupling in noncentrosymmetric materials is critical for controlling the internal fields which give rise to Rashba interactions. We apply time- and angle-resolved photoemission spectroscopy (trARPES) to study …
View article: Terahertz-induced tunnel ionization drives coherent Raman-active phonon in Bismuth
Terahertz-induced tunnel ionization drives coherent Raman-active phonon in Bismuth Open
Driving coherent lattice motion with THz pulses has emerged as a novel pathway for achieving dynamic stabilization of exotic phases that are inaccessible in equilibrium quantum materials. In this work, we present a previously unexplored me…
View article: Multi-Mode Front Lens for Momentum Microscopy: Part II Experiments
Multi-Mode Front Lens for Momentum Microscopy: Part II Experiments Open
We have experimentally demonstrated different operating modes for the front lenses of the momentum microscopes described in Part I. Measurements at energies from vacuum UV at a high-harmonic generation (HHG)-based source to the soft and ha…
View article: Coherent light control of a metastable hidden state
Coherent light control of a metastable hidden state Open
Metastable phases present a promising route to expand the functionality of complex materials. Of particular interest are light-induced metastable phases that are inaccessible under equilibrium conditions, as they often host new, emergent p…
View article: Time- and angle-resolved photoemission data of 1T-TaS2
Time- and angle-resolved photoemission data of 1T-TaS2 Open
Time- and angle-resolved photoemission spectroscopy data of bulk 1T-TaS2, acquired using the XUV trARPES setup at the Fritz-Haber-Institute of the Max-Planck Society, Berlin, Germany, and the UV trARPES setup at Stanford University, Califo…
View article: Time- and angle-resolved photoemission data of 1T-TaS2
Time- and angle-resolved photoemission data of 1T-TaS2 Open
Time- and angle-resolved photoemission spectroscopy data of bulk 1T-TaS2, acquired using the XUV trARPES setup at the Fritz-Haber-Institute of the Max-Planck Society, Berlin, Germany, and the UV trARPES setup at Stanford University, Califo…
View article: Development of deflector mode for spin-resolved time-of-flight photoemission spectroscopy
Development of deflector mode for spin-resolved time-of-flight photoemission spectroscopy Open
Spin- and angle-resolved photoemission spectroscopy (“spin-ARPES”) is a powerful technique for probing the spin degree-of-freedom in materials with nontrivial topology, magnetism, and strong correlations. Spin-ARPES faces severe experiment…
View article: Ultrafast measurements of mode-specific deformation potentials of Bi$_2$Te$_3$ and Bi$_2$Se$_3$
Ultrafast measurements of mode-specific deformation potentials of Bi$_2$Te$_3$ and Bi$_2$Se$_3$ Open
Quantifying electron-phonon interactions for the surface states of topological materials can provide key insights into surface-state transport, topological superconductivity, and potentially how to manipulate the surface state using a stru…
View article: Spectroscopic evidence for topological band structure in FeTe$_{0.55}$Se$_{0.45}$
Spectroscopic evidence for topological band structure in FeTe$_{0.55}$Se$_{0.45}$ Open
FeTe$_{0.55}$Se$_{0.45}$(FTS) occupies a special spot in modern condensed matter physics at the intersections of electron correlation, topology, and unconventional superconductivity. The bulk electronic structure of FTS is predicted to be …
View article: Signatures of the exciton gas phase and its condensation in monolayer 1T-ZrTe2
Signatures of the exciton gas phase and its condensation in monolayer 1T-ZrTe2 Open
The excitonic insulator (EI) is a Bose-Einstein condensation (BEC) of excitons bound by electron-hole interaction in a solid, which could support high-temperature BEC transition. The material realization of EI has been challenged by the di…
View article: Influence of local symmetry on lattice dynamics coupled to topological surface states
Influence of local symmetry on lattice dynamics coupled to topological surface states Open
Herein we investigate coupled electron-lattice dynamics in the topological insulator Bi2Te3 with time-resolved photoemission and time-resolved x-ray diffraction. It is well established that coherent phonons can be launched by optical excit…
View article: Influence of local symmetry on lattice dynamics coupled to topological surface states
Influence of local symmetry on lattice dynamics coupled to topological surface states Open
We investigate coupled electron-lattice dynamics in the topological insulator Bi2Te3 with time-resolved photoemission and time-resolved x-ray diffraction. It is well established that coherent phonons can be launched by optical excitation, …
View article: Coherent Light Control of a Metastable Hidden Phase
Coherent Light Control of a Metastable Hidden Phase Open
Metastable phases present a promising route to expand the functionality of complex materials. Of particular interest are light-induced metastable phases that are inaccessible under equilibrium conditions, as they often host new, emergent p…
View article: Connection between coherent phonons and electron-phonon coupling in Sb (111)
Connection between coherent phonons and electron-phonon coupling in Sb (111) Open
We report time- and angle-resolved photoemission spectroscopy (trARPES) measurements on the Sb(111) surface. We observe band- and momentum-dependent binding-energy oscillations in the bulk and surface bands driven by $A_{1g}$ and $E_{g}$ c…
View article: Evidences for the exciton gas phase and its condensation in monolayer 1T-ZrTe2
Evidences for the exciton gas phase and its condensation in monolayer 1T-ZrTe2 Open
The excitonic insulator (EI) is a Bose-Einstein condensation (BEC) of excitons bound by electron-hole interaction in a solid, which could support high-temperature BEC transition. The material realization of EI has been elusive, which is fu…
View article: Expanding the momentum field of view in angle-resolved photoemission systems with hemispherical analyzers
Expanding the momentum field of view in angle-resolved photoemission systems with hemispherical analyzers Open
In photoelectron spectroscopy, the measured electron momentum range is intrinsically related to the excitation photon energy. Low photon energies <10 eV are commonly encountered in laser-based photoemission and lead to a momentum range …
View article: All-Optical Probe of Three-Dimensional Topological Insulators Based on High-Harmonic Generation by Circularly Polarized Laser Fields
All-Optical Probe of Three-Dimensional Topological Insulators Based on High-Harmonic Generation by Circularly Polarized Laser Fields Open
We report the observation of a novel nonlinear optical response from the prototypical three-dimensional topological insulator Bi$_2$Se$_3$ through the process of high-order harmonic generation. We find that the generation efficiency increa…
View article: Connection between coherent phonons and electron-phonon coupling in Sb (111)
Connection between coherent phonons and electron-phonon coupling in Sb (111) Open
We report time- and angle-resolved photoemission spectroscopy measurements on the Sb(111) surface. We observe band- and momentum-dependent binding-energy oscillations in the bulk and surface bands driven by $A_{1g}$ and $E_{g}$ coherent ph…
View article: Angle-resolved photoemission studies of quantum materials
Angle-resolved photoemission studies of quantum materials Open
The physics of quantum materials is dictated by many-body interactions and mathematical concepts such as symmetry and topology that have transformed our understanding of matter. Angle-resolved photoemission spectroscopy (ARPES), which dire…
View article: Tuning time and energy resolution in time-resolved photoemission spectroscopy with nonlinear crystals
Tuning time and energy resolution in time-resolved photoemission spectroscopy with nonlinear crystals Open
Time- and angle-resolved photoemission spectroscopy is a powerful probe of electronic band structures out of equilibrium. Tuning time and energy resolution to suit a particular scientific question has become an increasingly important exper…
View article: Mode-Selective Coupling of Coherent Phonons to the Bi2212 Electronic Band Structure
Mode-Selective Coupling of Coherent Phonons to the Bi2212 Electronic Band Structure Open
Cuprate superconductors host a multitude of low-energy optical phonons. Using time- and angle-resolved photoemission spectroscopy, we study coherent phonons in Bi_{2}Sr_{2}Ca_{0.92}Y_{0.08}Cu_{2}O_{8+δ}. Sub-meV modulations of the electron…
View article: Visualizing Exotic Orbital Texture in the Single-Layer Mott Insulator 1T-TaSe2
Visualizing Exotic Orbital Texture in the Single-Layer Mott Insulator 1T-TaSe2 Open
Mott insulating behavior is induced by strong electron correlation and can lead to exotic states of matter such as unconventional superconductivity and quantum spin liquids. Recent advances in van der Waals material synthesis enable the ex…
View article: Band-Resolved Imaging of Photocurrent in a Topological Insulator
Band-Resolved Imaging of Photocurrent in a Topological Insulator Open
We study the microscopic origins of photocurrent generation in the topological insulator Bi_{2}Se_{3} via time- and angle-resolved photoemission spectroscopy. We image the unoccupied band structure as it evolves following a circularly pola…