Magnetic circular dichroism in 4d→4f resonant photoemission and photoabsorption of Gd metal

Starke, K.; Navas, E.; Arenholz, Elke; Hu, Z.; Baumgarten, L.; Laan, G. van der; Chen, C. T.; Kaindl, G.

doi:10.1103/physrevb.55.2672

Cited by 51 publications

(37 citation statements)

References 16 publications

(13 reference statements)

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“…The shape of the rare earth N 4,5 (4d → 4f) edges (Ogasawara and Kotani, 1995;Starke et al, 1997) and the 3d transition metal M 2,3 (3p→ 3d) edges (van der Laan, 1991b) are similar to the actinide O 4,5 , due to the fact that each exhibit a giant resonance. In all three of these cases, the core-valence electrostatic interactions dominate the core spin-orbit interaction.…”

Section: Electron Energy-loss Spectroscopymentioning

confidence: 99%

Nature of the5fstates in actinide metals

2009

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Actinide elements produce a plethora of interesting physical behaviors due to the 5f states. This review compiles and analyzes progress in understanding of the electronic and magnetic structure of the 5f states in actinide metals. Particular interest is given to electron energy-loss spectroscopy and many-electron atomic spectral calculations, since there is now an appreciable library of core d → valence f transitions for Th, U, Np, Pu, Am, and Cm. These results are interwoven and discussed against published experimental data, such as x-ray photoemission and absorption spectroscopy, transport measurements, and electron, x-ray, and neutron diffraction, as well as theoretical results, such as density-functional theory and dynamical mean-field theory.

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Section: Electron Energy-loss Spectroscopymentioning

confidence: 99%

Nature of the5fstates in actinide metals

2009

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“…By contrast, the higher energy spectral structure (>115 eV) is influenced by more extended final states that interact with the continuum bands, giving rise to Fano resonances and clearly leaving the ionic limit [29,[49][50][51][52].…”

Section: A the N 45 Spectramentioning

confidence: 99%

Core and shallow-cored- tof-shell excitations in rare-earth metals

et al. 2011

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We report on the results of probing the light lanthanide metals Ce, Pr, and Nd with inelastic x-ray and electron scattering. Transmission electron microscope-based electron spectroscopy and nonresonant inelastic x-ray scattering are shown to be in a high degree of accord, and here serve as complementary probes of electronic structure. The high resolution and high signal-to-noise electron technique allows for the measurement of the complex and subtle excitation spectra in the lanthanide metals, validating the applicability of the screened trivalent atomic model used for these materials. In addition, the momentum transfer dependence of the x-ray scattering is extracted and compared against atomic calculations for the most tightly bound excitonic resonances, which provides a direct test of the predicted atomic radial wave functions.

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“…For parallel orientation of photon spin and sample magnetization (∆M = +1 transitions), the intermediate 8 P 5/2 state at around 148 eV is preferentially populated; for antiparallel orientation (∆M = −1 transitions), by contrast, the only allowed excitation is into the higher 8 P 9/2 state at around 150 eV. 24 The large difference in absorption coefficient for opposite magnetization directions (Fig. 2a) corresponds to a difference in the absorptive part ∆β ≡ β + − β − = ∆µ λ/(4π) of the refractive index n ± = 1 − δ ± − iβ ± .…”

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“…The photon energy resolution was set to about 100 meV (FWHM) which is well below the intrinsic width of the narrow Gd N 4,5 pre-edge absorption lines. 24 The photon energy interval from 110 to 200 eV was scanned at slow speed by a synchronized movement of monochromator and undulator. This synchronization is essential to properly normalize the absorption spectra and allows one to exploit the high flux of the undulator beamline of about 10 14 photons/(s · 100 mA · 0.1% bandwidth) over a wide energy range.…”

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Prediction of huge x-ray Faraday rotation at the GdN4,5threshold

et al. 2002

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X-ray absorption spectra in a wide energy range around the 4d-4f excitation threshold of Gd were recorded by total electron yield from in-plane magnetized Gd metal films. Matching the experimental spectra to tabulated absorption data reveals unprecedented short light absorption lengths down to 3 nm. The associated real parts of the refractive index for circularly polarized light propagating parallel or antiparallel to the Gd magnetization, determined through the KramersKronig transformation, correspond to a magneto-optical Faraday rotation of 0.7• per atomic layer. This finding shall allow the study of magnetic structure and magnetization dynamics of lanthanide elements in nanosize systems and dilute alloys.PACS numbers: 78.20.Ls, 78.70.Dm Resonance enhancements of X-ray magnetic scattering cross sections at inner-shell absorption edges 1,2 have been used for years to investigate the magnetic structure of lanthanide 3 and actinide 4 systems in the hard X-ray regime (above 2 keV). The experimental demonstration of large changes in the specularly reflected X-ray intensity at the Fe L 2,3 edge 5 upon magnetization reversal initiated the ongoing search for magneto-optical (MO) effects in the soft X-ray regime, 6,7,8,9,10,11,12 as well as their application to element-specific studies of heteromagnetic systems. 13,14,15,16,17,18 Yet, in analyzing soft X-ray MO signals from thin films and multilayer systems with thicknesses comparable to the X-ray wavelength, previous investigations have shown 5,13,18 that a comparison with model calculations 19of the reflected specular intensity (based on the Fresnel equations) is needed in order to extract a layerresolved sample magnetization profile. Several experimental determinations of soft X-ray MO constants have been reported 8,9,10 for ferromagnetic transition metals in the region of the L 2,3 thresholds, but none so far for the lanthanide elements, despite their wide recognition as, e.g., constituents of exchange-spring magnets 20 and magnetic recording media 21 . Only recently has it been demonstrated that sizeable MO signals are obtained from lanthanide elements in the soft X-ray region at the N 4,5 thresholds. 22Here we show that calibrated N 4,5 absorption spectra from magnetized Gd metal, recorded with circularly polarized (CP) light in the energy interval from 110 to 200 eV, yield an X-ray absorption coefficient up to three times larger than expected. The magnetizationdependent absorption of CP light at the Gd N 4,5 giant resonance maximum, described by the imaginary part of the refraction index, is accompanied by a huge change in light propagation speed upon magnetization reversal, a dispersive effect described by the real part of the refraction index, implying a Faraday rotation (FR) of about 0.7• per atomic layer. Thus, even very small or diluted lanthanide systems are expected to show a measurable effect.The absorption experiments were performed at the high-resolution UE56 undulator beamline 23 of the Berliner Elektronenspeicherring für Synchrotronstrahlung (BES...

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Magnetic circular dichroism in 4d→4f resonant photoemission and photoabsorption of Gd metal

Cited by 51 publications

References 16 publications

Nature of the5fstates in actinide metals

Nature of the5fstates in actinide metals

Core and shallow-cored- tof-shell excitations in rare-earth metals

Prediction of huge x-ray Faraday rotation at the GdN4,5threshold

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