Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userComputational Framework for Angle-Resolved Photoemission Spectroscopy
116
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We have developed the numerical software package $chinook$, designed for the simulation of photoemission matrix elements. This quantity encodes a depth of information regarding the orbital structure of the underlying wavefunctions from which photoemission occurs. Extraction of this information is often nontrivial, owing to the influence of the experimental geometry and photoelectron interference, precluding straightforward solutions. The $chinook$ code has been designed to simulate and predict the ARPES intensity measured for arbitrary experimental configuration, including photon-energy, polarization and spin-projection, as well as consideration of both surface-projected slab and bulk models. This framework then facilitates an efficient interpretation of the photoemission experiment, allowing for a deeper understanding of the electronic structure in addition to the design of new experiments which leverage the matrix element effects towards the objective of selective photoemission from states of particular interest.
rate research
Read More
The compound UTe2 has recently been shown to realize spin triplet superconductivity from a non-magnetic normal state. This has sparked intense research activity, including theoretical analyses that suggest the superconducting order parameter to be topologically nontrivial. However, the underlying electronic band structure is a critical factor for these analyses, and remains poorly understood. Here, we present high resolution angle resolved photoemission (ARPES) measurements covering multiple planes in the 3D Brillouin zone of UTe2, revealing distinct Fermi-level features from two orthogonal quasi-one dimensional light electron bands and one heavy band. The electronic symmetries are evaluated in comparison with numerical simulations, and the resulting picture is discussed as a platform for unconventional many-body order.
Progress in performing angle-resolved photoemission spectroscopy (ARPES) with high spatial resolution in the order of 1~$mu$m or less (nanoARPES) has opened the possibility to map the spectral function of solids on this tiny scale and thereby obtain detailed information on the materials emph{local} electronic band structure and many-body interactions. Recently, nanoARPES has been used to study simple electronic devices, based on two-dimensional materials, with the possibility of tuning the carrier type and density by field effect-gating, and while passing a current through the device. It was demonstrated that nanoARPES can detect possible changes in the materials electronic structure in these situations and that it can map the local doping, conductance and mobility. This article reviews these first emph{in operando} ARPES results on devices, discusses the resulting new insights, as well as the perspectives for future developments of the technique.
We have carried out high-resolution angle-resolved photoemission measurements on the Cebased heavy fermion compound CePt2In7 that exhibits stronger two-dimensional character than the prototypical heavy fermion system CeCoIn5. Multiple Fermi surface sheets and a complex band structure are clearly resolved. We have also performed detailed band structure calculations on CePt2In7. The good agreement found between our measurements and the calculations suggests that the band renormalization effect is rather weak in CePt2In7. A comparison of the common features of the electronic structure of CePt2In7 and CeCoIn5 indicates that CeCoIn5 shows a much stronger band renormalization effect than CePt2In7. These results provide new information for understanding the heavy fermion behaviors and unconventional superconductivity in Ce-based heavy fermion systems.
Nonequilibrium calculations in the presence of an electric field are usually performed in a gauge, and need to be transformed to reveal the gauge-invariant observables. In this work, we discuss the issue of gauge invariance in the context of time-resolved angle-resolved pump/probe photoemission. If the probe is applied while the pump is still on, one must ensure that the calculations of the observed photocurrent are gauge invariant. We also discuss the requirement of the photoemission signal to be positive and the relationship of this constraint to gauge invariance. We end by discussing some technical details related to the perturbative derivation of the photoemission spectra, which involve processes where the pump pulse photoexcites electrons due to nonequilibrium effects.
Performing time and angle resolved photoemission spectroscopy (tr-ARPES) at high momenta necessitates extreme ultraviolet laser pulses, which are typically produced via high harmonic generation (HHG). Despite recent advances, HHG-based setups still require large pulse energies (hundreds of $mu$J to mJ) and their energy resolution is limited to tens of meV. Here, we present a novel 11 eV tr-ARPES setup that generates a flux of $5times10^{10}$ photons/s and achieves an unprecedented energy resolution of 16 meV. It can be operated at high repetition rates (up to 250 kHz) while using input pulse energies down to 3 $mu$J. We demonstrate these unique capabilities by simultaneously capturing the energy and momentum resolved dynamics in two well-separated momentum space regions of a charge density wave material ErTe$_3$. This novel setup offers opportunity to study the non-equilibrium band structure of solids with exceptional energy and time resolutions at high repetition rates.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
