X-ray absorption and dichroism of transition metals and their compounds

Groot, Frank M. F. de

doi:10.1016/0368-2048(93)02041-j

Cited by 649 publications

(379 citation statements)

References 374 publications

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“…This indicates an increase of the number of electrons at the Ru sites: for open shells the energy position of the XAS spectrum shifts to lower energies with decreasing valence. 27 At the maximum of the L 3 line it is seen that doping with one electron per formula unit (four Ru atoms) results in a shift of about an quarter of an eV, in agreement with the notion that a valence change of one electron results in a shift of the transition metal L 2,3 edge of the order of 1 eV. 28 …”

Section: Results A: Cu and Ru Valencesupporting

confidence: 68%

Correlation effects in CaCu3Ru4O12

Hollmann

Maignan

et al. 2013

Phys. Rev. B

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We have investigated the electronic structure of CaCu3Ru4O12 and LaCu3Ru4O12 using soft x-ray photoelectron and absorption spectroscopy together with band structure and cluster configuration interaction calculations. We found the Cu to be in a robust divalent ionic state while the Ru is more itinerant in character and stabilizes the metallic state. Substitution of Ca by La predominantly affects the Ru states. We observed strong correlation effects in the Cu 3d states affecting the valence band line shape considerably. Using resonant photoelectron spectroscopy at the Cu L3 edge we were able to unveil the position of the Zhang-Rice singlet states in the one-electron removal spectrum of the Cu with respect to the Ru-derived metallic bands in the vicinity of the chemical potential.

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Section: Results A: Cu and Ru Valencesupporting

confidence: 68%

Correlation effects in CaCu3Ru4O12

Hollmann

Maignan

et al. 2013

Phys. Rev. B

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“…Spin-orbit coupling splits the transition-metal L2,3 edge into two components, L2 and L3, corresponding to the 2p1/2 → 3d and 2p3/2 → 3d transitions respectively 25,26 . The most striking evidence of the changes in the Mn valence state towards Mn 3+ is observed with the systematic shift of the L2 and L3 spectral weights towards lower photon energies [26][27][28][29] as a function of increasing strain. The spectral shift is due to changes in the electrostatic energy at the Mn site driven by the decrease in the 3d count, which leads to shifts of both the core level and the final-state wavefunctions 27,30 .…”

Section: Textmentioning

confidence: 92%

Strain-Engineered Oxygen Vacancies in CaMnO₃ Thin Films

et al. 2017

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We demonstrate a novel pathway to control and stabilize oxygen vacancies in complex transition-metal oxide thin films. Using atomic layer-by-layer pulsed laser deposition (PLD) from two separate targets, we synthesize high-quality singlecrystalline CaMnO 3 films with systematically varying oxygen vacancy defect formation energies as controlled by coherent tensile strain. The systematic increase of the oxygen vacancy content in CaMnO 3 as a function of applied in-plane strain is observed and confirmed experimentally using high-resolution soft X-ray absorption spectroscopy (XAS) in conjunction with bulk-sensitive hard X-ray photoemission spectroscopy (HAXPES). The relevant defect states in the densities of states are identified and the vacancy content in the films quantified using the combination of first-principles theory and core−hole multiplet calculations with holistic fitting. Our findings open up a promising avenue for designing and controlling new ionically active properties and functionalities of complex transition-metal oxides via strain-induced oxygen-vacancy formation and ordering.

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“…The subtraction was made so that the deduced spectrum becomes similar to the Mn L 3 -edge XAS of MnO. 41 Because MnO is a paramagnetic insulator at room temperature and an antiferromagnetic insulator below T N ∼ 120 K, oxidized Mn atoms in the β = 1.60 sample would not contribute to the ferromagnetism.…”

Section: Appendixmentioning

confidence: 99%

Effects of off-stoichiometry on the spin polarization at the Co2MnβGe0.38/MgO interfa

et al. 2012

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We have studied the electronic and magnetic states of Mn and Co atoms at the Co 2 Mn β Ge 0.38 (CMG)/MgO (β = 0.67-1.8) interfaces, which constitute CMG/MgO/CMG magnetic tunnel junctions, by means of x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroisms (XMCDs) at the Mn and Co L 2,3 edges and compared the deduced Co and Mn magnetic moments by the density-functional calculations with the coherent potential approximation (CPA). As the Mn content β increased, the intensity of Mn L 2,3 XMCD decreased, in agreement with the result of the CPA calculation, which showed the resultant reduction of charges and spin moment on Mn atoms because of the delocalization of Mn 3d electrons with increasing β. The Co spin magnetic moment for all the samples increased with decreasing β, again consistent with the present calculation and the previous density-functional calculation by Picozzi et al. that the Co Mn antisite has a larger magnetic moment than that of Co atoms at the regular sites and reduces the spin polarization at the Fermi level and hence the tunnel magnetoresistance ratio.

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X-ray absorption and dichroism of transition metals and their compounds

Cited by 649 publications

References 374 publications

Correlation effects in CaCu3Ru4O12

Correlation effects in CaCu3Ru4O12

Strain-Engineered Oxygen Vacancies in CaMnO₃ Thin Films

Effects of off-stoichiometry on the spin polarization at the Co2MnβGe0.38/MgO interfa

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X-ray absorption and dichroism of transition metals and their compounds

Cited by 649 publications

References 374 publications

Correlation effects in CaCu3Ru4O12

Correlation effects in CaCu3Ru4O12

Strain-Engineered Oxygen Vacancies in CaMnO3 Thin Films

Effects of off-stoichiometry on the spin polarization at the Co2MnβGe0.38/MgO interfa

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Strain-Engineered Oxygen Vacancies in CaMnO₃ Thin Films