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論文

Resonant inelastic X-ray scattering study of entangled spin-orbital excitations in superconducting PrFeAsO$$_{0.7}$$

野村 拓司*; 原田 慈久*; 丹羽 秀治*; 石井 賢司*; 石角 元志*; 社本 真一; Jarrige, I.*

Physical Review B, 94(3), p.035134_1 - 035134_9, 2016/07

 被引用回数:9 パーセンタイル:49.94(Materials Science, Multidisciplinary)

Fe-$$L_{3}$$吸収端での共鳴非弾性X線散乱(RIXS)を用いて、典型的な鉄系超伝導体PrFeAsO$$_{0.7}$$の単結晶で、低エネルギー電子励起スペクトルを測定した。

論文

Observation of momentum-resolved charge fluctuations proximate to the charge-order phase using resonant inelastic X-ray scattering

吉田 雅洋*; 石井 賢司; 中 惇*; 石原 純夫*; Jarrige, I.*; 池内 和彦*; 村上 洋一*; 工藤 一貴*; 小池 洋二*; 永田 知子*; et al.

Scientific Reports (Internet), 6, p.23611_1 - 23611_8, 2016/03

 被引用回数:0 パーセンタイル:0(Multidisciplinary Sciences)

In strongly correlated electron systems, enhanced fluctuations in the proximity of the ordered states of electronic degrees of freedom often induce anomalous electronic properties such as unconventional superconductivity. While spin fluctuations in the energy-momentum space have been studied widely using inelastic neutron scattering, other degrees of freedom, i.e., charge and orbital, have hardly been explored thus far. Here, we use resonant inelastic X-ray scattering to observe charge fluctuations proximate to the charge-order phase in transition metal oxides. In the two-leg ladder of Sr$$_{14-x}$$Ca$$_x$$Cu$$_{24}$$O$$_{41}$$, charge fluctuations are enhanced at the propagation vector of the charge order ($$mathbf{q}_mathrm{CO}$$) when the order is melted by raising the temperature or by doping holes. In contrast, charge fluctuations are observed not only at $$mathbf{q}_mathrm{CO}$$ but also at other momenta in a geometrically frustrated triangular bilayer lattice of LuFe$$_2$$O$$_4$$. The observed charge fluctuations have a high energy ($$sim$$ 1 eV), suggesting that the Coulomb repulsion between electrons plays an important role in the formation of the charge order.

論文

Resonant inelastic X-ray scattering study of electronic excitations in insulating K$$_{0.83}$$Fe$$_{1.53}$$Se$$_2$$

Gretarsson, H.*; 野村 拓司; Jarrige, I.*; Lupascu, A.*; Upton, M. H.*; Kim, J.*; Casa, D.*; Gog, T.*; Yuan, R. H.*; Chen, Z. G.*; et al.

Physical Review B, 91(24), p.245118_1 - 245118_8, 2015/06

 被引用回数:6 パーセンタイル:33.5(Materials Science, Multidisciplinary)

We report an Fe $$K$$-edge resonant inelastic X-ray scattering (RIXS) study of K$$_{0.83}$$Fe$$_{1.53}$$Se$$_2$$. This material is an insulator, unlike many parent compounds of iron-based superconductors. We found a sharp excitation around 1 eV, which is resonantly enhanced when the incident photon energy is tuned near the pre-edge region of the absorption spectrum. The spectral weight and line shape of this excitation exhibit clear momentum dependence. In addition, we observe momentum-independent broad interband transitions at higher excitation energy of 3-7 eV. Calculations based on a 70 band $$dp$$ orbital model, using a moderate $$U_{rm eff}$$ = 2.5 eV, indicate that the 1 eV feature originates from the correlated Fe 3$$d$$ electrons, with a dominant $$d_{xz}$$ and $$d_{yz}$$ orbital character. We find that a moderate $$U_{rm eff}$$ yields a satisfying agreement with the experimental spectra, suggesting that the electron correlations in the insulating and metallic iron based superconductors are comparable.

論文

Extending resonant inelastic X-ray scattering to the extreme ultraviolet

Wray, L. A.*; Huang, S.-W.*; Jarrige, I.*; 池内 和彦*; 石井 賢司; Li, J.*; Qiu, Z. Q.*; Hussain, Z.*; Chuang, Y.-D.*

Frontiers in Physics (Internet), 3, p.32_1 - 32_11, 2015/05

 被引用回数:4

In resonant inelastic X-ray scattering (RIXS), core hole resonance modes are used to enhance coupling between photons and low energy electronic degrees of freedom. Resonating with shallow core holes accessed in the extreme ultraviolet (EUV) can provide greatly improved energy resolution at standard resolving power, but has been found to often yield qualitatively different spectra than similar measurements performed with higher energy X-rays. This paper uses experimental data and multiplet-based numerical simulations for the M-edges of Co-, Ni-, and Cu-based Mott insulators to review the properties that distinguish EUV RIXS from more commonly performed higher energy measurements. Key factors such as the origin of the strong EUV elastic line and advantages of EUV spectral functions over soft X-ray RIXS for identifying intrinsic excitation line shapes are discussed.

論文

Kondo interactions from band reconstruction in YbInCu$$_4$$

Jarrige, I.*; 小谷 章雄*; 山岡 人志*; 辻井 直人*; 石井 賢司; Upton, M.*; Casa, D.*; Kim, J. H.*; Gog, T.*; Hancock, J. N.*

Physical Review Letters, 114(12), p.126401_1 - 126401_5, 2015/03

 被引用回数:8 パーセンタイル:58.5(Physics, Multidisciplinary)

We combine resonant inelastic X-ray scattering and model calculations in the Kondo lattice compound YbInCu$$_4$$, a system characterized by a dramatic increase in Kondo temperature and associated valence fluctuations below a first-order valence transition at T $$simeq$$ 42 K. The bulk-sensitive, element-specific, and valence-projected charge excitation spectra reveal an unusual quasigap in the Yb-derived state density which drives an instability of the electronic structure and renormalizes the low-energy effective Hamiltonian at the transition. Our results provide long-sought experimental evidence for a link between temperature-driven changes in the low-energy Kondo scale and the higher-energy electronic structure of this system.

論文

Towards optimizing the performance of self-regenerating Pt-based perovskite catalysts

Jarrige, I.*; 石井 賢司; 松村 大樹; 西畑 保雄; 吉田 雅洋*; 岸 浩史*; 谷口 昌司*; 上西 真里*; 田中 裕久*; 笠井 秀明*; et al.

ACS Catalysis, 5(2), p.1112 - 1118, 2015/02

 被引用回数:14 パーセンタイル:43.47(Chemistry, Physical)

Self-regenerating automotive catalysts owe their remarkable performance to the repeated motion of the precious metal atoms in and out of the perovskite lattice under fluctuating oxidizing and reducing conditions, preventing coalescence of the metal nanoparticles. Here we use resonant inelastic X-ray scattering to characterize the occupied and unoccupied Pt 5d states in two self-regenerating Pt-perovskite catalysts, CaTi$$_{0.95}$$Pt$$_{0.05}$$O$$_3$$ and CaZr$$_{0.95}$$Pt$$_{0.05}$$O$$_3$$. Upon reduction, the element and symmetry-specific charge excitation spectra reveal a sizeable hybridization between the Pt 5d and the Ti 3d or Zr 4d states at the interface between the nanoparticles and the perovskite, which involves the occupied states and is thus invisible in X-ray absorption spectra. A correlation is found between the strength of this d-band hybridization and the proportion of Pt nanoparticles that remain buried below the surface during reduction, indicating that the motion of the Pt atoms towards the surface is hindered by this hybridization specifically, rather than by the Pt-O bonding. These results provide direct evidence that the strength of the metal-metal d-band hybridization plays a pivotal role in determining the efficiency of self-regeneration in perovskite catalysts.

論文

Electronic structure of BaTiO$$_{3}$$ using resonant X-ray emission spectroscopy at the Ba-L$$_{3}$$ and Ti K absorption edges

吉井 賢資; 米田 安宏; Jarrige, I.*; 福田 竜生; 西畑 保雄; 鈴木 知史; 伊藤 嘉昭*; 寺嶋 孝仁*; 吉門 新三*; 福島 整*

Journal of Physics and Chemistry of Solids, 75(3), p.339 - 343, 2014/03

 被引用回数:7 パーセンタイル:36.72(Chemistry, Multidisciplinary)

強誘電体BaTiO$$_{3}$$3について、共鳴X線発光(RXES)及び部分蛍光法を用いたX線吸収分光(PFY-XAS)により電子状態を分析した。実験はSPring8の原子力機構ビームラインBL14B1と物質・材料研究機構ビームラインBL15XUで行った。Ba L$$_{3}$$吸収端でのPFY-XASスペクトルは、過去の文献とは異なり、キュリー点上下で変化しなかった。これは、Ba$$^{2+}$$イオンの位置はキュリー点で変位しないか変位が小さいことを示唆する。また、Ti K吸収端でのRXESスペクトルからは、発光ピークのエネルギーは入射光エネルギーによらずほぼ一定であった。この結果は、Ti 3d軌道が非局在的な性質を持っており、それによりTiイオンが変位して電気双極子の生成して強誘電体となるという、理論計算から提案された機構を支持することが分かった。

論文

Momentum-resolved resonant inelastic X-ray scattering on a single crystal under high pressure

吉田 雅洋*; 石井 賢司; Jarrige, I.*; 綿貫 徹; 工藤 一貴*; 小池 洋二*; 熊谷 健一*; 平岡 望*; 石井 啓文*; Tsuei, K.-D.*; et al.

Journal of Synchrotron Radiation, 21(1), p.131 - 135, 2014/01

 被引用回数:3 パーセンタイル:22.1(Instruments & Instrumentation)

A single-crystal momentum-resolved resonant inelastic X-ray scattering (RIXS) experiment under high pressure using an originally designed diamond anvil cell (DAC) is reported. The diamond-in/diamond-out geometry was adopted with both the incident and scattered beams passing through a 1 mm-thick diamond. This enabled us to cover wide momentum space keeping the scattering angle condition near 90$$^{circ}$$. Elastic and inelastic scattering from the diamond was drastically reduced using a pinhole placed after the DAC. Measurement of the momentum-resolved RIXS spectra of Sr$$_{2.5}$$Ca$$_{11.5}$$Cu$$_{24}$$O$$_{41}$$ at the Cu $$K$$-edge was thus successful. Though the inelastic intensity becomes weaker by two orders than the ambient pressure, RIXS spectra both at the center and the edge of the Brillouin zone were obtained at 3 GPa and low-energy electronic excitations of the cuprate were found to change with pressure.

論文

Instrumental upgrades of the RIXS spectrometer at BL11XU at SPring-8

石井 賢司; Jarrige, I.*; 吉田 雅洋*; 池内 和彦*; 稲見 俊哉; 村上 洋一*; 水木 純一郎

Journal of Electron Spectroscopy and Related Phenomena, 188, p.127 - 132, 2013/06

 被引用回数:12 パーセンタイル:62.69(Spectroscopy)

Two recent instrumental upgrades of the inelastic X-ray scattering spectrometer installed at BL11XU at SPring-8 are reported. The first one is a multianalyzer system, where we can simultaneously use three crystal analyzers aligned perpendicularly to the scattering plane. In a test measurement of polycrystalline $$alpha$$-PtO$$_2$$, the inelastic spectra obtained with each respective analyzer showed a completely identical lineshape, and a slight difference ($$le$$ 10%) in intensity. The system enhances the experimental efficiency, and allows for simultaneous scan at three momenta for a single-crystal sample. The second development is a polarization analyzer for the scattered photons. A pyrolytic graphite (PG) crystal is placed in front of the detector and serves as a polarization-analyzer crystal, using the (006) reflection for the Cu $$K$$-edge. We succeeded to observe clear polarization dependence in the $$d$$-$$d$$ excitations of KCuF$$_3$$.

論文

Probing the Ba 5d states in BaTiO$$_{3}$$ and BaSO$$_{4}$$; A Resonant X-ray emission study at the Ba-L$$_{3}$$ edge

吉井 賢資; Jarrige, I.; 鈴木 知史; 松村 大樹; 西畑 保雄; 米田 安宏; 福田 竜生; 田村 和久; 伊藤 嘉昭*; 向山 毅*; et al.

Journal of Physics and Chemistry of Solids, 73(9), p.1106 - 1110, 2012/09

 被引用回数:11 パーセンタイル:47.94(Chemistry, Multidisciplinary)

強誘電体BaTiO$$_{3}$$のBa 5d軌道の電子状態を放射光共鳴発光により調べ、誘電性を持たないBaSO$$_{4}$$と比較した。Ba-L$$_{3}$$吸収端近傍において共鳴発光スペクトルを測定したところ、両方の化合物ともBa 5d電子は局在していることがわかった。一方、共鳴発光を利用した部分蛍光法吸収スペクトルを測定したところ、BaTiO$$_{3}$$のほうがBaSO$$_{4}$$よりもエネルギー幅の広いピークが観測された。すなわち、BaTiO$$_{3}$$のBa 5d軌道は、O 2p軌道と混成していることがわかった。これは、BaTiO$$_{3}$$の強誘電性はTi-Oの混成により発現するとされてきた従来の見解と異なり、Baイオンも強誘電相転移に何らかの役割を果たすことを示唆する。

論文

Resonant inelastic X-ray scattering study of charge excitations in superconducting and nonsuperconducting PrFeAsO$$_{1-y}$$

Jarrige, I.*; 野村 拓司; 石井 賢司; Gretarsson, H.*; Kim, Y.-J.*; Kim, J.*; Upton, M.*; Casa, D.*; Gog, T.*; 石角 元志*; et al.

Physical Review B, 86(11), p.115104_1 - 115104_4, 2012/09

 被引用回数:8 パーセンタイル:38.69(Materials Science, Multidisciplinary)

鉄系高温超伝導体PrFeAsO$$_{0.7}$$とその親物質であるPrFeAsOに対して、運動量分解した共鳴非弾性X線散乱を初めて観測した。主な結果は次の2点である。まず、第一に、16バンドの$$dp$$模型を用いて、低エネルギーの励起が$$xz$$, $$yz$$軌道の特性を有する$$dd$$バンド内遷移に支配されていることを示し、電子相関に強く依存していることを示す。これによって、クーロン斥力$$U$$とフント結合$$J$$を見積もることができる。特に軌道依存した電子相関における$$J$$の果たす役割が明らかとなる。第二に、短距離の反強磁性相関が$$Gamma$$点での励起の説明には不可欠であることから、超伝導状態においてもそれが存在することが示される。

論文

Electronic excitations around the substituted atom in La$$_2$$Cu$$_{1-y}$$N$$_y$$O$$_4$$ as seen via resonant inelastic X-ray scattering

石井 賢司; 筒井 健二; 池内 和彦*; Jarrige, I.; 水木 純一郎; 平賀 晴弘*; 山田 和芳*; 遠山 貴己*; 前川 禎通; 遠藤 康夫*; et al.

Physical Review B, 85(10), p.104509_1 - 104509_5, 2012/03

 被引用回数:3 パーセンタイル:16.62(Materials Science, Multidisciplinary)

We perform a resonant inelastic X-ray scattering (RIXS) study of Ni-substituted La$$_2$$CuO$$_4$$ and Cu-substituted La$$_2$$NiO$$_4$$.Resonantly enhanced charge-transfer excitations are successfully observed by tuning the incident photon energy to the $$K$$-edge of the substituted element. These excitations display a very weak momentum dependence, evidencing their local character. We find a shift in the energy of the onset edge of these features compared with the non-substituted compounds La$$_2$$CuO$$_4$$ and La$$_2$$NiO$$_4$$. This shift is quantitatively reproduced by exact diagonalization calculations of the RIXS spectra. RIXS is shown to be a powerful tool to probe the electronic states of substituted elements and to understand their interaction with surrounding atoms.

論文

Resonant inelastic X-ray scattering at Ba-L$$_{3}$$ edge in BaTiO$$_{3}$$

吉井 賢資; Jarrige, I.; 松村 大樹; 西畑 保雄; 鈴木 知史; 伊藤 嘉昭*; 向山 毅*; 栃尾 達紀*; 篠塚 寛志*; 福島 整*

Japanese Journal of Applied Physics, 50(9), p.09NE03_1 - 09NE03_4, 2011/09

 被引用回数:2 パーセンタイル:10.82(Physics, Applied)

強誘電体BaTiO$$_{3}$$のBa-L$$_{3}$$吸収端における共鳴非弾性X線散乱測定をSPring-8ビームラインBL15XUで行った。まず、非弾性散乱X線の一つBa-L$$alpha$$$$_{1}$$線に分光器のエネルギーを合わせ、誘電性を示さないBaSO$$_{4}$$を対照物質としてBa-5d吸収スペクトルを測定したところ、BaTiO$$_{3}$$のスペクトルは幅が太いことがわかった。分子軌道計算を行ったところ、Ba-5d軌道とO-3p軌道が共有結合的な性質を有し、エネルギーバンドを作っていることがわかった。BaTiO$$_{3}$$の強誘電性はTi-Oの共有結合性による原子変位がその起源とされているが、この実験事実はBa-Oの共有結合も重要であることを示唆する。また、Ba-L$$alpha$$$$_{1}$$非弾性X線スペクトルを吸収端近傍で測定したところ、Ba-5d軌道は上述の通り酸素とバンドを作っているものの、局在的であることを示すデータが得られた。この測定により、非占有状態の局在性の指標に関する情報が得られること、また、考えられる幾つかの応用についても議論する。

論文

Polarization-analyzed resonant inelastic X-ray scattering of the orbital excitations in KCuF$$_3$$

石井 賢司; 石原 純夫*; 村上 洋一*; 池内 和彦*; 葛下 かおり*; 稲見 俊哉; 大和田 謙二; 吉田 雅洋; Jarrige, I.; 多々見 央*; et al.

Physical Review B, 83(24), p.241101_1 - 241101_4, 2011/06

 被引用回数:21 パーセンタイル:68.08(Materials Science, Multidisciplinary)

We report a Cu $$K$$-edge resonant inelastic X-ray scattering (RIXS) study of orbital excitations in KCuF$$_3$$. By performing the polarization analysis of the scattered photons, we disclose that the excitation between the $$e_g$$ orbitals and the excitations from $$t_{2g}$$ to $$e_g$$ exhibit distinct polarization dependence. The polarization dependence of the respective excitations is interpreted based on a phenomenological consideration of the symmetry of the RIXS process that yields a necessary condition for observing the excitations. In addition, we show that the orbital excitations are dispersionless within our experimental resolution.

論文

Momentum-resolved electronic excitations in the Mott insulator Sr$$_2$$IrO$$_4$$ studied by resonant inelastic X-ray scattering

石井 賢司; Jarrige, I.; 吉田 雅洋; 池内 和彦*; 水木 純一郎; 大橋 啓*; 高山 知弘*; 松野 丈夫*; 高木 英典*

Physical Review B, 83(11), p.115121_1 - 115121_5, 2011/03

 被引用回数:67 パーセンタイル:91.69(Materials Science, Multidisciplinary)

We report an Ir $$L_3$$-edge resonant inelastic X-ray scattering (RIXS) measurement of the low-lying electronic excitations in Sr$$_2$$IrO$$_4$$ over the complete Brillouin zone of the IrO$$_2$$ plane. A remarkably strong inelastic signal which exceeds the elastic scattering in intensity is observed. Peaks observed at 0.5, 3.2, and 6.0 eV are respectively ascribed to an interband transition across the Mott gap and charge-transfer excitations from the O $$2p$$ band to the Ir $$5d$$ bands. The dispersion of the Mott gap excitation is found to be particularly weak. This is interpreted as a signature of the narrow $$5d$$ bands of the novel Mott insulating state of Sr$$_2$$IrO$$_4$$ induced by the strong spin-orbit interaction.

論文

Resonant inelastic X-ray scattering of La$$_2$$Cu$$_{0.95}$$Ni$$_{0.05}$$O$$_4$$

石井 賢司; 池内 和彦*; Jarrige, I.; 水木 純一郎; 平賀 晴弘*; 山田 和芳*; 筒井 健二; 遠山 貴己*; 前川 禎通*; 遠藤 康夫*; et al.

Physica C, 470(Suppl.1), p.S155 - S157, 2010/12

 被引用回数:0 パーセンタイル:0(Physics, Applied)

Substitution of a specific element for a component is often used to elucidate its role in the superconductors. For a complete understanding of the substitution effect not only on the superconductivity but also on the electronic states, element-selective experiments are required. In this respect, resonant inelastic X-ray scattering (RIXS) has proven to be a powerful experimental technique enabling element-selective diagnosis of charge excitations. By tuning the incident photon energy to a given absorption edge of the element, the excitations involving the element are resonantly enhanced. In addition, RIXS has the advantage that momentum dependence can be measured. Using RIXS, we have measured the electronic excitations at the substituting sites in La$$_2$$Cu$$_{0.95}$$Ni$$_{0.05}$$O$$_4$$ and La$$_2$$Ni$$_{0.95}$$Cu$$_{0.05}$$O$$_4$$. Near the absorption edge of the substituting element, namely the Ni $$K$$-edge for La$$_2$$Cu$$_{0.95}$$Ni$$_{0.05}$$O$$_4$$ and the Cu $$K$$-edge for La$$_2$$Ni$$_{0.95}$$Cu$$_{0.05}$$O$$_4$$, charge transfer excitations from the 2$$p$$ level of neighboring oxygen to the upper Hubbard band of the substituted Ni/Cu are observed. Experimental spectra are qualitatively reproduced by a theoretical calculation based on a $$d$$-$$p$$ model.

論文

Temperature dependence of the electronic structure of Sr$$_{14}$$Cu$$_{24}$$O$$_{41}$$ studied by resonant inelastic X-ray scattering

吉田 雅洋; 石井 賢司; 池内 和彦*; Jarrige, I.; 村上 洋一*; 水木 純一郎; 筒井 健二; 遠山 貴己*; 前川 禎通*; 工藤 一貴*; et al.

Physica C, 470(Suppl.1), p.S145 - S146, 2010/12

 被引用回数:4 パーセンタイル:23.57(Physics, Applied)

Sr$$_{14-x}$$Ca$$_x$$Cu$$_{24}$$O$$_{41}$$ (SCCO), which is composed of two-leg ladders and edge-sharing chains, is the first superconducting cuprate without CuO$$_2$$ planes. By substituting Ca for Sr, holes are transferred from the chains to the ladders. It was recently shown that charge ordering (CO) along the leg direction in the ladder occurs at $$x=0$$ and the periodicity is five times the unit length along the c axis. In order to investigate the electronic excitations associated with the CO, we carried out resonant inelastic X-ray scattering (RIXS) experiments for SCCO ($$x=0,6$$). Cu-$$K$$ RIXS can directly probe the momentum-dependent electronic excitations related to the Cu site, which are resonantly enhanced by tuning the incident photon energy to the Cu $$K$$-edge. We measured the q dependence of the intraband excitations, which is associated with the dynamics of doped holes in the Zhang-Rice singlet band. The intensity is enhanced at the momentum $${bf q}=(q_{rm rung},q_{rm leg})=(0,2pi/5)$$ corresponding to the periodicity of the CO in $$x=0$$, while the temperature dependence of the enhancement is different for $$x=0$$ and $$x=6$$. We discuss the relationship between our experimental results and the occurrence of the CO.

論文

Resonant inelastic X-ray scattering in single-crystal superconducting PrFeAsO$$_{0.7}$$

Jarrige, I.; 石井 賢司; 吉田 雅洋; 福田 竜生; 池内 和彦*; 石角 元志*; 平岡 望*; Tsuei, K.-D.*; 鬼頭 聖*; 伊豫 彰*; et al.

Physica C, 470(Suppl.1), p.S377 - S378, 2010/10

 被引用回数:4 パーセンタイル:23.57(Physics, Applied)

Resonant inelastic X-ray scattering (RIXS) spectra at the Fe K-edge were measured for a single-crystal of the iron oxypnictide superconductor PrFeAsO$$_{0.7}$$ ($$T_{rm C}$$ = 42 K). They disclose a weak, broad feature centered around 4.5 eV energy loss, which is slightly resonantly enhanced when the incident energy is tuned to the vicinity of the $$4p$$ white line. We tentatively ascribe it to the charge-transfer excitation between As $$4p$$ and Fe $$3d$$.

論文

Resonant inelastic X-ray scattering in electronically quasi-zero-dimensional CuB$$_2$$O$$_4$$

Hancock, J. N.*; Chabot-Couture, G.*; Li, Y.*; Petrakovski$u{i}$, G. A.*; 石井 賢司; Jarrige, I.; 水木 純一郎; Devereaux, T. P.*; Greven, M.*

Physical Review B, 80(9), p.092509_1 - 092509_4, 2009/09

 被引用回数:20 パーセンタイル:65.27(Materials Science, Multidisciplinary)

We present a resonant inelastic scattering (RIXS) study using of CuB$$_2$$O$$_4$$, which contains a lattice of CuO$$_4$$ plaquettes electronically isolated by B$$^{+3}$$ ions. The observed Cu $$K$$-edge spectra show a small number of well-separated features, and the simple electronic structure of CuB$$_2$$O$$_4$$ allows us to explore RIXS phenomenology. We find a low-energy feature that cannot be attributed to the same charge-transfer excitation discussed in other cuprates and is likely a $$d to d$$ transition thought to be forbidden under common considerations of $$K$$-edge RIXS.

論文

Thermally activated charge transfer in a Prussian blue derivative probed by resonant inelastic X-ray scattering

Jarrige, I.; Cai, Y. Q.*; 石井 啓文*; 平岡 望*; Bleuzen, A.*

Applied Physics Letters, 93(5), p.054101_1 - 054101_3, 2008/08

 被引用回数:9 パーセンタイル:38.53(Physics, Applied)

Charge-transfer excitation is at the source of the photoinduced magnetism observed in several Prussian blue molecule-based magnets. Using resonant inelastic X-ray scattering and X-ray absorption spectroscopy, we probe directly the thermally-activated charge transfer in a photomagnetic Fe-Co cyanide, Cs$$_{0.7}$$Co$$_{4}$$[Fe(CN)$$_{6}$$]$$_{2.9}$$[V]$$_{1.1}$$. 16H$$_{2}$$O, where [V] represents [Fe(CN)$$_{6}$$] vacancies. The temperature dependence of both Co and Fe valence ratios is estimated for the first time in one cooling run, thus yielding a more complete picture of the temperature-induced cooperative electronic modifications. This novel approach, benefiting from relatively short acquisition times, opens the possibility for realtime characterization of the photoinduced magnetism in molecule-based magnets.

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