0000000000307384
AUTHOR
Steinn Ymir Agustsson
showing 8 related works from this author
Suppression of the vacuum space-charge effect in fs-photoemission by a retarding electrostatic front lens
2021
Review of scientific instruments 92(5), 053703 (2021). doi:10.1063/5.0046567
Observation of an excitonic Mott transition through ultrafast core-cum-conduction photoemission spectroscopy
2020
Time-resolved soft-X-ray photoemission spectroscopy is used to simultaneously measure the ultrafast dynamics of core-level spectral functions and excited states upon excitation of excitons in WSe$_2$. We present a many-body approximation for the Green's function, which excellently describes the transient core-hole spectral function. The relative dynamics of excited-state signal and core levels reveals a delayed core-hole renormalization due to screening by excited quasi-free carriers, revealing an excitonic Mott transition. These findings establish time-resolved core-level photoelectron spectroscopy as a sensitive probe of subtle electronic many-body interactions and an ultrafast electronic…
Néel Vector Induced Manipulation of Valence States in the Collinear Antiferromagnet Mn 2 Au
2020
The coupling of real and momentum space is utilized to tailor electronic properties of the collinear metallic antiferromagnet Mn2Au by aligning the real space Neel vector indicating the direction o...
Temperature-Dependent Change of the Electronic Structure in the Kondo Lattice System $YbRh_{2}Si_{2}$
2021
Seminar, Deutschland; Journal of physics / Condensed matter 00(00), 1-20 (2021). doi:10.1088/1361-648X/abe479
Néel Spin-Orbit Torque Driven Antiferromagnetic Resonance in Mn2Au Probed by Time-Domain THz Spectroscopy
2018
We observe the excitation of collective modes in the terahertz (THz) range driven by the recently discovered Neel spin-orbit torques (NSOTs) in the metallic antiferromagnet Mn_{2}Au. Temperature-dependent THz spectroscopy reveals a strong absorption mode centered near 1 THz, which upon heating from 4 to 450 K softens and loses intensity. A comparison with the estimated eigenmode frequencies implies that the observed mode is an in-plane antiferromagnetic resonance (AFMR). The AFMR absorption strength exceeds those found in antiferromagnetic insulators, driven by the magnetic field of the THz radiation, by 3 orders of magnitude. Based on this and the agreement with our theory modeling, we inf…
Robust hybridization gap in the Kondo insulator YbB12 probed by femtosecond optical spectroscopy
2021
In heavy fermions the relaxation dynamics of photoexcited carriers has been found to be governed by the low energy indirect gap ${\mathrm{E}}_{g}$ resulting from hybridization between localized moments and conduction band electrons. Here, carrier relaxation dynamics in a prototype Kondo insulator $\mathrm{Yb}{\mathrm{B}}_{12}$ is studied over a large range of temperatures and over three orders of magnitude. We utilize the intrinsic nonlinearity of dynamics to quantitatively determine microscopic parameters, such as electron-hole recombination rate. The extracted value reveals that hybridization is accompanied by a strong charge transfer from localized $4f$ levels. The results imply the pres…
Emitter-site specificity of hard x-ray photoelectron Kikuchi-diffraction
2020
New journal of physics 22(10), 103002 (1-13) (2020). doi:10.1088/1367-2630/abb68b
Time-resolved core-level photoemission data of tungsten diselenide
2020
Pump-probe core-level photoemission spectroscopy data of tungsten diselenide (WSe2) measured using an electron momentum microscope at the FLASH Free-electron laser.