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Studies for the commissioning of FERMI@Elettra
Jurij Urbančič, 2011, magistrsko delo

Najdeno v: osebi
Ključne besede: laser na proste elektrone, sinhrotron, sinhrotronska svetloba, ultra-relativistični snop elektronov, ultraviolična svetloba, magistrske naloge
Objavljeno: 15.10.2013; Ogledov: 2519; Prenosov: 12
URL Polno besedilo (0,00 KB)
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Self-amplified photo-induced gap quenching in a correlated electron material
Jurij Urbančič, Eich Steffen, Mathias Stefan, 2016, izvirni znanstveni članek

Opis: Capturing the dynamic electronic band structure of a correlated material presents a powerful capability for uncovering the complex couplings between the electronic and structural degrees of freedom. When combined with ultrafast laser excitation, new phases of matter can result, since far-from-equilibrium excited states are instantaneously populated. Here, we elucidate a general relation between ultrafast non-equilibrium electron dynamics and the size of the characteristic energy gap in a correlated electron material. We show that carrier multiplication via impact ionization can be one of the most important processes in a gapped material, and that the speed of carrier multiplication critically depends on the size of the energy gap. In the case of the charge-density wave material 1T-TiSe 2 , our data indicate that carrier multiplication and gap dynamics mutually amplify each other, which explains—on a microscopic level—the extremely fast response of this material to ultrafast optical excitation. Self-amplified photo-induced gap quenching in a correlated electron material. Available from: [accessed Apr 20, 2017].
Najdeno v: osebi
Ključne besede: high harmonic generation, charge-density wave material, 1T-TiSe2, non-equilibrium electron dynamics, ultrafast surface science
Objavljeno: 20.04.2017; Ogledov: 1274; Prenosov: 0
.pdf Polno besedilo (1,10 MB)

Time- and angle-resolved photoemission spectroscopy with optimized high-harmonic pulses using frequency-doubled Ti:Sapphire lasers
Steffen Eich, Jurij Urbančič, 2014, izvirni znanstveni članek

Opis: Time- and angle-resolved photoemission spectroscopy (trARPES) using femtosecond extreme ultraviolet high harmonics has recently emerged as a powerful tool for investigating ultrafast quasiparticle dynamics in correlated-electron materials. However, the full potential of this approach has not yet been achieved because, to date, high harmonics generated by 800 nm wavelength Ti:Sapphire lasers required a trade-off between photon flux, energy and time resolution. Photoemission spectroscopy requires a quasi-monochromatic output, but dispersive optical elements that select a single harmonic can significantly reduce the photon flux and time resolution. Here we show that 400 nm driven high harmonic extreme-ultraviolet trARPES is superior to using 800 nm laser drivers since it eliminates the need for any spectral selection, thereby increasing photon flux and energy resolution to <150 meV while preserving excellent time resolution of about 30 fs.
Najdeno v: osebi
Ključne besede: angle-resolved photoemission spectroscopy, ARPES, high harmonic generation, ultrafast surface science
Objavljeno: 20.04.2017; Ogledov: 1247; Prenosov: 0
.pdf Polno besedilo (1,80 MB)

Orbital-dependent electron dynamics in Fe-pnictide superconductors
A. Thamizhavel, Damjan Krizmancic, Giovanni De Ninno, Jurij Urbančič, Primož Rebernik Ribič, Barbara Ressel, G. Adhikary, Kalobaran Maiti, Matija Stupar, 2018, izvirni znanstveni članek

Opis: We report on orbital-dependent quasiparticle dynamics in EuFe 2 As 2, a parent compound of Fe-based superconductors, and a way to experimentally identify this behavior using time-and angle-resolved photoelectron spectroscopy across the spin density wave transition. We observe two different relaxation timescales for photoexcited d x z/d y z and d x y electrons. While the itinerant d x z/d y z electrons relax faster through the electron-electron scattering channel, d x y electrons form a quasiequilibrium state with the lattice due to their localized character, and the state decays slowly. Our findings suggest that electron correlation in Fe pnictides is an important property, which should carefully be taken into account when describing the electronic properties of both parent and carrier-doped compounds, and therefore establish a strong connection with cuprates
Najdeno v: osebi
Ključne besede: photoelectron dynamics, Fe based superconductors
Objavljeno: 29.11.2018; Ogledov: 98; Prenosov: 0
.pdf Polno besedilo (2,37 MB)

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