Time-Resolved XUV absorption spectroscopy and magnetic circular dichroism at the Ni $M_{2,3}$-edges

Abstract

Ultrashort optical pulses can trigger a variety of non-equilibrium processes in magnetic thin films affecting electrons and spins on femtosecond timescales. In order to probe the charge and magnetic degrees of freedom simultaneously, we developed an x-ray streaking technique that has the advantage of providing a jitter-free picture of absorption cross section changes. In this paper, we present an experiment based on this approach which we performed using five photon probing energies at the Ni $M_{2,3}$-edges. This allowed us to retrieve the absorption and magnetic circular dichroism time traces, yielding detailed information on transient modifications of electron and spin populations close to the Fermi level. Our findings suggest that the observed charge and magnetic dynamics both depend on the XUV probing wavelength, and can be described, at least qualitatively, by assuming ultrafast energy shifts of the electronic and magnetic elemental absorption resonances, as reported in recent work. However, our analysis also hints at more complex changes, highlighting the need for further experimental and theoretical analysis in order to gain a thorough understanding of the interplay of electronic and spin degrees of freedom in optically excited magnetic thin films.

References in corpus (18)

• Super-Diffusive Spin-Transport as a Mechanism of Ultrafast Demagnetization
• The Ultrafast Einstein-De Haas Effect
• Influence of laser-excited electron distributions on the x-ray magnetic circular dichroism spectra: Implications for femtosecond demagnetization in Ni
• Revealing the nature of the ultrafast magnetic phase transition in Ni by correlating extreme ultraviolet magneto-optic and photoemission spectroscopies
• Role of critical spin fluctuations in ultrafast demagnetization of transition-metal rare-earth alloys
• Femtosecond X-ray magnetic circular dichroism absorption spectroscopy at an X-ray free electron laser
• Generation of high-frequency strain waves during femtosecond demagnetization of Fe/MgO films
• Magneto-Optical Functions at the 3p resonances of Fe, Co, and Ni: Ab-initio description and experiment
• Element specificity of transient extreme ultra-violet magnetic dichroism
• Distinct Ultrafast Electronic and Magnetic Response in M-edge Magnetic Circular Dichroism
• Laser-induced ultrafast demagnetization and perpendicular magnetic anisotropy reduction in a Co${}_{88}$Tb${}_{12}$ thin film with stripe domains
• Analysis of the linear relationship between asymmetry and magnetic moment at the M-edge of 3d transition metals
• Structural dynamics during laser induced ultrafast demagnetization
• Supervised learning of an opto-magnetic neural network with ultrashort laser pulses
• Simultaneous two-color snapshot view on ultrafast charge and spin dynamics in a Fe-Cu-Ni tri-layer
• Element-resolved ultrafast demagnetization rates in ferrimagnetic CoDy
• Single shot time-resolved magnetic x-ray absorption at a Free Electron Laser
• X-ray detection of ultrashort spin current pulses in synthetic antiferromagnets