Stefan Mathias

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An experimental setup for time- and angle-resolved photoemission spectroscopy using a femtosecond 1 kHz high harmonic light source and a two-dimensional electron analyzer for parallel energy and momentum detection is presented. A selection of the 27th harmonic (41.85 eV) from the harmonic spectrum of the light source is achieved with a multilayer MoSi(More)
The study of ultrafast dynamics in magnetic materials provides rich opportunities for greater fundamental understanding of correlated phenomena in solid-state matter, because many of the basic microscopic mechanisms involved are as-yet unclear and are still being uncovered. Recently, two different possible mechanisms have been proposed to explain ultrafast(More)
The underlying physics of all ferromagnetic behavior is the cooperative interaction between individual atomic magnetic moments that results in a macroscopic magnetization. In this work, we use extreme ultraviolet pulses from high-harmonic generation as an element-specific probe of ultrafast, optically driven, demagnetization in a ferromagnetic Fe-Ni alloy(More)
Intense femtosecond (10(-15) s) light pulses can be used to transform electronic, magnetic and structural order in condensed-matter systems on timescales of electronic and atomic motion. This technique is particularly useful in the study and in the control of materials whose physical properties are governed by the interactions between multiple degrees of(More)
Uncovering the physical mechanisms that govern ultrafast charge and spin dynamics is crucial for understanding correlated matter as well as the fundamental limits of ultrafast spin-based electronics. Spin dynamics in magnetic materials can be driven by ultrashort light pulses, resulting in a transient drop in magnetization within a few hundred femtoseconds.(More)
We use few-femtosecond soft x-ray pulses from high-harmonic generation to extract element-specific demagnetization dynamics and hysteresis loops of a compound material for the first time. Using a geometry where high-harmonic beams are reflected from a magnetized Permalloy grating, large changes in the reflected intensity of up to 6% at the M absorption(More)
Ultrashort pulses of extreme ultraviolet light from high-harmonic generation are a new tool for probing coupled charge, spin, and phonon dynamics with element specificity, attosecond pump-probe synchronization, and time resolution of a few femtoseconds in a tabletop apparatus. In this paper, we address an important question in magneto-optics that has(More)
Hybridization of atomic orbitals in graphene on Ni(111) opens a large energy gap of ≈2.8 eV between non-hybridized states at the K-point. Here we use alkali metal adsorbate to reduce and even eliminate this energy gap, and also identify a mechanism responsible for decoupling graphene from the Ni substrate without intercalation of atomic species underneath(More)
We report on the observation of a giant spin-orbit splitting of quantum-well states in the unoccupied electronic structure of a Bi monolayer on Cu(111). Up to now, Rashba-type splittings of this size have been reported exclusively for surface states in a partial band gap. With these quantum-well states we have experimentally identified a second class of(More)
Emrah Turgut,1 Dmitriy Zusin,1 Dominik Legut,2,3 Karel Carva,3,4 Ronny Knut,1 Justin M. Shaw,5 Cong Chen,1 Zhensheng Tao,1 Hans T. Nembach,5 Thomas J. Silva,5 Stefan Mathias,6 Martin Aeschlimann,7 Peter M. Oppeneer,4 Henry C. Kapteyn,1 Margaret M. Murnane,1 and Patrik Grychtol1 1Department of Physics and JILA, University of Colorado, Boulder, Colorado(More)