High-resolution nonresonant x-ray Raman scattering study on rare earth phosphate nanoparticles

Huotari, Simo; Suljoti, Edlira; Sahle, Christoph J.; Rädel, Stephanie; Monaco, G.; Groot, Frank M. F. de

doi:10.1088/1367-2630/17/4/043041

Cited by 8 publications

(4 citation statements)

References 35 publications

(61 reference statements)

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“…Several NIXS studies, also on uranium compounds, show experimentally and theoretically how the multiplet excitations develop with increasing momentum transfer 45,[50][51][52][53][54][55][56][57] . However, for convenience of the reader we recapitulate briefly the principle of NIXS: when working at large momentum transfers the expansion of the transition operator exp(i q r) in spherical harmonics cannot be truncated after the first term, thus giving rise to excitations due to quadru-, octupole and higher order contribution in S( q,ω).…”

Section: Resultsmentioning

confidence: 99%

Direct bulk-sensitive probe of 5 f symmetry in URu ₂ Si ₂

Sundermann

Haverkort

Agrestini

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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The second-order phase transition into a hidden order phase in URu 2 Si 2 goes along with an order parameter that is still a mystery, despite 30 years of research. However, it is understood that the symmetry of the order parameter must be related to the symmetry of the low-lying local electronic f-states. Here, we present results of a spectroscopic technique, namely core-level nonresonant inelastic X-ray scattering (NIXS). This method allows for the measurement of local high-multipole excitations and is bulk-sensitive. The observed anisotropy of the scattering function unambiguously shows that the 5f ground-state wave function is composed mainly of the Γ 1 with majority Jz = |4 + |−4 and/or Γ 2 singlet states. The incomplete dichroism indicates the possibility that quantum states of other irreducible representation are mixed into the ground state. strongly correlated electron systems | X-ray spectroscopy | crystal-electric field | heavy fermions | hidden order I n heavy fermion rare earth or actinide compounds, the f electrons are well localized at high temperatures, but as temperature is lowered, hybridization with conduction electrons becomes increasingly effective, resulting in a more itinerant f -electron character at low temperatures. These hybridized f electrons form narrow bands and have large effective masses. Quasiparticle interaction effects in these narrow bands are responsible for the many exciting phenomena present in heavy fermion compounds: multipolar order (1), unconventional superconductivity (2), or quantum criticality (3). The hidden order phase in URu2Si2 is one example of the exotic low-temperature phases found in this material class. URu2Si2 is a tetragonal heavy fermion compound that undergoes two phase transitions, the nonmagnetic hidden order (HO) transition at THO = 17.5 K, which involves an appreciable loss of entropy, and a superconducting transition at about 1.5 K (4-7). Below the HO transition, small-ordered magnetic moments were observed in the earlier studies but were determined later to belong to a parasitic minority phase. With applied pressure (p ≥ 0.7 GPa), the HO order is replaced by an antiferromagnetic phase with large-ordered moments (so-called LMAF -phase) (8). The order parameter of the HO phase has been the subject of intense investigations for more than 30 years but, so far, has remained hidden, which has been the inspiration for its name. This second-order transition into an electronically ordered state involves a reconstruction of the Fermi surface (9, 10) and a change of quasiparticle scattering rate (11). The Fermi surfaces of the HO and high-pressure LMAF phase are very similar (12).In URu2Si2 three-energy scales have been identified: a hybridization gap of ∆ hyb ≈ 13 meV [150 K] (13) that opens below 27 K, another gap that opens in the HO phase with ∆HO ≈ 4.1 meV [50 K] in the charge (9, 10, 14, 15) as well as spin channel (16,17), and a resonance mode that appears in the HO gap at ∼ =1.6 meV [18 K], also in both channels (18)(19)(20). Furthermore, with entering ...

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Section: Resultsmentioning

confidence: 99%

Direct bulk-sensitive probe of 5 f symmetry in URu ₂ Si ₂

Sundermann

Haverkort

Agrestini

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…At higher momentum transfer values the measured cross section (2) is sensitive to dipole forbidden transitions. Studies of the high-order multiplet features in the 3d transition metals, rare earths and actinides are examples of how to exploit this fact (Gordon et al, 2008;Caciuffo et al, 2010;Sen Gupta et al, 2011;Huotari et al, 2015). Information from different excitation channels provides access to the entire unoccupied density of states (Soininen et al, 2005;Inkinen et al, 2014).…”

Section: Methodsmentioning

confidence: 99%

A miniature closed-circle flow cell for high photon flux X-ray scattering experiments

Sahle

Henriquet

Schroer

et al. 2015

J Synchrotron Radiat

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A closed-circle miniature flow cell for high X-ray photon flux experiments on radiation-sensitive liquid samples is presented. The compact cell is made from highly inert material and the flow is induced by a rotating magnetic stir bar, which acts as a centrifugal pump inside the cell. The cell is ideal for radiation-sensitive yet precious or hazardous liquid samples, such as concentrated acids or bases. As a demonstration of the cell's capabilities, X-ray Raman scattering spectroscopy data on the oxygen K-edge of liquid water under ambient conditions are presented.

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“…9,10 In addition, XRS at the rare earth N and O edges has been extensively discussed. 11,12 The XAS-MCD measurements are carried out in order to elucidate the orbital and spin magnetic moment at the selected magnetic ion. In the analysis of the MCD signal, the orbital-and the spin moment sum rules play central roles.…”

Section: Introductionmentioning

confidence: 99%

Magnetic circular dichroism in hard x-ray Raman scattering as a probe of local spin polarization

Takahashi

Hiraoka

2019

Phys. Rev. B

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We argue that the magnetic circular dichroism (MCD) of the hard x-ray Raman scattering (XRS) could be used as an element selective probe of local spin polarization. The magnitude of the XRS-MCD signal is directly proportional to the local spin polarization when the angle between the incident wavevector and the magnetization vector is 135 • or −45 • . By comparing the experimental observation and the configuration interaction calculation at the L 2,3 and M 2,3 edges of ferromagnetic iron, we suggest that the integrated MCD signal in terms of the transferred energy could be used to estimate the local spin moment even in the case where the application of the spin sum-rule in X-ray absorption is questionable. We also point out that XRS-MCD signal could be observed at the M 1 edge with a magnitude comparable to that at the M 2,3 edge, although the spin-orbit coupling is absent in the core orbital. By combining the XRS-MCD at various edges, spin polarization distribution depending on the orbital magnetic quantum number would be determined.1 arXiv:1909.13490v1 [cond-mat.mtrl-sci] 30 Sep 2019 X-ray magnetic circular dichroism (MCD) has been one of the powerful tools to investigate the electronic structure in magnetic materials. Particularly, owing to the orbital and spin sum-rules, 1,2 the MCD in the soft x-ray absorption spectroscopy (XAS) has been playing crucial roles for elucidating the electronic structure at and around the absorption site. 3 The MCD measurements in x-ray emission and resonant inelastic scattering are also important tools to clarify the electronic excitations in magnetic materials. 4Recently, the MCD in the hard x-ray Raman scattering (XRS) at the Fe L 2,3 -edges in the ferromagnetic iron has been investigated. 5,6 The XRS is a kind of non-resonant inelasticx-ray scattering. 7 In the process of photon scattering, where an incident photon of energy ω i is absorbed and a photon of energy ω f is emitted, the electron system in the initial ground state of the energy E i is excited to the final state of the energyThe final state of the XRS is essentially the same with that of XAS: A core hole is left behind at the scattering site and an electron is added to the valence or conduction state.Therefore, the XRS intensity as a function of transferred energy is similar to the soft xray absorption coefficient as a function of the incident photon energy. Contrasting to the XAS, the hard-in-hard-out feature of the XRS is preferable for bulk sensitive measurements or the measurements under extreme conditions. In addition, the XRS can access the final states that are inaccessible by the dipole transition, because the non-dipole transition matrix elements become significant for shallow core excitation. By virtue of these features, the innercore-exciting XRS has been demonstrating its usefulness particularly to unveil the electronic state of materials under extreme conditions. 8 Recently, the electronic state of Fe in Fe 2 SiO 4 , Fe 2 O 3 and FeS under high pressure is discussed by analyzing the XRS spectra at the F...

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High-resolution nonresonant x-ray Raman scattering study on rare earth phosphate nanoparticles

Cited by 8 publications

References 35 publications

Direct bulk-sensitive probe of 5 f symmetry in URu ₂ Si ₂

Direct bulk-sensitive probe of 5 f symmetry in URu ₂ Si ₂

A miniature closed-circle flow cell for high photon flux X-ray scattering experiments

Magnetic circular dichroism in hard x-ray Raman scattering as a probe of local spin polarization

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High-resolution nonresonant x-ray Raman scattering study on rare earth phosphate nanoparticles

Cited by 8 publications

References 35 publications

Direct bulk-sensitive probe of 5 f symmetry in URu 2 Si 2

Direct bulk-sensitive probe of 5 f symmetry in URu 2 Si 2

A miniature closed-circle flow cell for high photon flux X-ray scattering experiments

Magnetic circular dichroism in hard x-ray Raman scattering as a probe of local spin polarization

Contact Info

Product

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Direct bulk-sensitive probe of 5 f symmetry in URu ₂ Si ₂

Direct bulk-sensitive probe of 5 f symmetry in URu ₂ Si ₂