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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

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

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

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.

口頭

Volume collapse transition in TmTe; Competition between strong correlation and $$f$$-$$d$$ hybridization at high pressure

Jarrige, I.; Rueff, J.-P.*; Shieh, S.*; 田口 宗孝*; 大石 泰生*; 松村 隆*; 石井 啓文*; 平岡 望*; Cai, Y.*

no journal, , 

The pressure-induced mixed-valent state in TmTe is investigated up to 10.6 GPa using resonant inelastic X-ray scattering (RIXS) and the Anderson impurity model (AIM). The volume collapse transition (VCT) which takes place over the 2-4.3 GPa range is accompanied by a strong increase in the 4$$f$$-5$$d$$ hybridization. The valence in the collapsed state is found to be 2.5, showing that the VCT is inconsistent with the commonly accepted picture of Tm$$^{2+}$$ to Tm$$^{3+}$$ conversion. At 6 GPa, a transition in both magnetic and electronic ground states occurs at constant valence and hybridization. This could be indicative of a non-trivial instability of the 4$$f$$ ground state such as a non Fermi liquid behavior.

口頭

Volume collapse transition in TmTe; Competition between strong correlation and f-d hybridization at high pressure

Jarrige, I.; Rueff, J.-P.*; Shieh, S.*; Wang, J.*; 松村 隆*; 石井 啓文*; 平岡 望*; Cai, Y.*

no journal, , 

The pressure-induced mixed-valent state in TmTe is investigated up to 10.6 GPa using resonant inelastic X-ray scattering (RIXS) and the Anderson impurity model (AIM). The volume collapse transition (VCT) which takes place over the 2$$sim$$4.3 GPa range is accompanied by a strong increase in the 4f-5d hybridization. The valence in the collapsed state is found to be $$sim$$2.5, showing that the VCT is inconsistent with the commonly accepted picture of Tm$$^{2+}$$ to Tm$$^{3+}$$ conversion. At 6 GPa, a transition in both magnetic and electronic ground states occurs at constant valence and hybridization. This could be indicative of a non-trivial instability of the 4f ground state such as a non Fermi liquid behavior.

口頭

LaMnO$$_{3}$$における圧力下金属絶縁体転移のX線発光と吸収分光法の測定

Jarrige, I.; Shieh, S.*; 石井 啓文*; 平岡 望*; Cai, Y.*

no journal, , 

Here we report on a spectroscopic investigation of the intricate interplays between electronic, magnetic and structural properties of LaMnO$$_{3}$$ across its pressure-induced insulator to metal transition (IMT) at 32 GPa. We measure the Mn K-beta fluorescence line by X-ray emission spectroscopy (XES) and the Mn K-egde by X-ray absorption spectroscopy in the partial fluorescence yield mode (PFY-XAS). The XES spectra disclose a high-spin to low-spin transition accompanying the IMT that points to strongly interwoven charge and spin degrees of freedom, which is reminiscent of the Mott perspective. On the other hand, close insight is gained on the structure from the Mn K pre-edge region, where evidence is found for a complete suppression of the Jahn-Teller distortions at the IMT. This is congruent with the scenario that the gap closure results from the progressive pressure-induced degeneracy of the majority-spin eg band, thus suggesting that the IMT in LaMnO$$_{3}$$ is not a plain Mott transition.

口頭

二次元検出器を用いた共鳴非弾性X線散乱の高分解能・高効率化

石井 賢司; Jarrige, I.; 池内 和彦; 吉田 雅洋; 石井 啓文*; 平岡 望*; 豊川 秀訓*

no journal, , 

近年、高輝度放射光を用いた共鳴非弾性X線散乱による電子励起状態の研究が行われるようになってきた。この手法を用いて物性とのかかわりの深い低エネルギーの励起を観測するためには、分光器の高分解能化は欠かせない。一方で、分解能を上げて検出するバンド幅を狭くすると検出効率が低下し、測定に時間がかかることになる。この点を克服するために、位置敏感型検出器を用いて複数のエネルギーを同時に測定する方法がHuotariらによって提案された。この方法は、最近APSの30IDに設置された分光器MERIXにおいても採用されている。この方法をSPring-8の非弾性ビームラインでも構築すべく、台湾ビームラインBL12XUでテスト実験を行った。検出器には、二次元ピクセルアレイ型のPILATUSを用いた。原理的には一次元検出器で可能であるが、二次元検出器を用いることで複数のアナライザーからの同時計測が可能になるなど、将来の拡張性が高い。結果、MnのK吸収端で約110meV、CuのK吸収端で約200meVの分解能を得た。講演では、現状の問題点,今後の展開と合わせて議論を行う予定である。

口頭

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

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

no journal, , 

鉄ニクタイドにおける超伝導の機構を解明するためには、その低エネルギーの電子励起状態を深く理解することが不可欠である。この低エネルギー励起を明らかにすることを目的として、アンダードープ領域にあるPrFeAsO$$_{0.7}$$(Tc=42K)について、鉄のK吸収端を用いた共鳴非弾性X線散乱(RIXS)の実験を行った。その結果、Fe-As間の電荷移動励起と考えられる分散の小さい励起がおよそ4eVに観測された。

口頭

Single-channel vs multi-channel Kondo effects; SmTe and TmTe studied via resonant inelastic X-ray scattering under high pressure

Jarrige, I.; Rueff, J.-P.*; Shieh, S.*; 田口 宗孝*; 大石 泰生*; 松村 武*; 石井 啓文*; 平岡 望*; Cai, Y. Q.*

no journal, , 

Using resonant inelastic X-ray scattering and the Anderson impurity model, we estimated the pressure dependence of the Sm and Tm valence and 4 f -5d hybridization in the respectively single and multi-channel Kondo compounds SmTe and TmTe. We observed a usual, continuous Kondo-like f delocalization for SmTe as a function of pressure. On the contrary, our results reveal that the f delocalization in TmTe is discontinuous, characterized by a previously unobserved plateau-like behavior between 4.3 and 6.5 GPa. This is interpreted as an experimental observation of the effect of culminating multi-channel Kondo scattering of d electrons from local moments on the electronic structure. Our study raises the interesting possibility that an NCK effect realized in a compressed mixed-valent f system could impede the concomitant electron delocalization.

口頭

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

Jarrige, I.; 石井 賢司; 福田 竜生; 吉田 雅洋; 石角 元志; 社本 真一; 平岡 望*; Tsuei, K.-D.*

no journal, , 

We have performed a resonant inelastic X-ray scattering (RIXS) measurement at the Fe K edge in a single crystal of the underdoped superconductor compound PrFeAsO$$_{0.7}$$ (Tc = 42 K). The dependence of the RIXS spectra upon the incident energy E1, measured with the momentum transfer Q = (0 0 6.5) which corresponds to (0,0), is observed to be nearly featureless. In the E1 = 7124 and 7125 eV spectra, we discern a feature centered around 4 eV which undergoes a slight resonant enhancement. The energy of this feature is reminiscent of the metal-ligand charge transfer in the cuprates, therefore we are tempted to ascribe it to the charge transfer between Fe 3d and As 4p.

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