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論文

$^{149}$ Sm synchrotron-radiation-based Mssbauer spectroscopy of Sm-based heavy fermion compounds

筒井智嗣; 東中隆二*; 水牧仁一朗*; 小林義男*; 中村仁*; 伊藤孝; 依田芳卓*; 松田達磨*; 青木勇二*; 佐藤英行*

Interactions (Internet), 245(1), p.9_1 - 9_10, 2024/12

https://doi.org/10.1007/s10751-024-01851-y

$^{149}$ Sm synchrotron-radiation-based Mssbauer spectroscopy has been applied to Sm-based heavy fermion intermetallics, SmAl $_{20}$ ( = Ti, V and Cr) and SmOs $_{4}$ Sb $_{12}$ . The isomer shifts obtained demonstrate that the Sm valence states in these compounds are intermediate. Since the difference of the isomer shifts in 22.502 keV $^{149}$ Sm Mssbauer effect between Sm $^{2+}$ and Sm $^{3+}$ state is comparable to the 2nd order Doppler shift, consideration of the 2nd order Doppler shift is required to precisely discuss Sm valence state through the shifts of the Mssbauer spectra. In addition, the plots of the isomer shifts obtained by the Mssbauer spectroscopy against the Sm valence states estimated from Sm L-edge X-ray absorption spectroscopy exhibit a linear correlation except for that in SmOsSb $_{12}$ . This implies that the origin of the intermediate valence state in SmOsSb $_{12}$ differs from that in SmAl $_{20}$ ( = Ti, V and Cr).

論文

$^{149}$ Sm synchrotron-radiation-based Mssbauer and SR studies of SmRuGe $_{13}$

筒井智嗣; 伊藤孝; 中村仁*; 吉田実生*; 小林義男*; 依田芳卓*; 中村惇平*; 幸田章宏*; 東中隆二*; 青木大*; et al.

Interactions (Internet), 245(1), p.55_1 - 55_9, 2024/12

https://doi.org/10.1007/s10751-024-01900-6

$^{149}$ Sm SR-based Mssbauer and muon spin relaxation (SR) spectroscopies have been applied to SmRuGe $_{13}$ . The temperature dependence of the $^{149}$ Sm SR-based Mssbauer spectra in the paramagnetic state implies the presence of dynamical nuclear Zeeman and/or quadrupole interactions. The time differential SR spectra also exhibit a marked temperature dependence in the paramagnetic state, indicating the presence of magnetic fluctuation in SmRuGe $_{13}$ at least. These results in the present work infer that the dynamical hyperfine interactions observed using the mutually complementary spectroscopic methods are connected with the mechanism of the heavy fermion behavior in SmRuGe $_{13}$ .

論文

Ca-induced phonon softening in BaTiO $_{3}$ revealed by inelastic X-ray and neutron scattering

木村耕治*; 筒井智嗣*; 山本裕太*; 中埜彰俊*; 川村啓介*; 梶本亮一; 蒲沢和也*; Martin, A.*; Webber, K. G.*; 柿本健一*; et al.

Physical Review B, 110(13), p.134314_1 - 134314_10, 2024/10

https://doi.org/10.1103/PhysRevB.110.134314

被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)

We performed inelastic X-ray and neutron scattering (IXS and INS) experiments for (Ba,Ca)TiO $_{3}$ single crystals to elucidate the effect of Ca doing on the atomic dynamics. Dispersion relations of transverse phonons in BaTiO $_{3}$ , (Ba $_{0.9}$ Ca $_{0.1}$ )TiO $_{3}$ , and (Ba $_{0.8}$ Ca $_{0.2}$ )TiO $_{3}$ were determined. The -site-O vibrational mode as well as the acoustic mode were observed both by IXS and INS, whereas the Ti-O soft mode was detected only by INS. It was found that the -site-O vibration exhibits significant softening with increasing Ca concentration, while the Ti-O soft mode is almost unaffected by the Ca doping. This finding is discussed in comparison with the polarization hysteresis loops and piezoelectric coefficients of (Ba,Ca)TiO $_{3}$ . It is indicated that the softening of the -site-O vibration contributes to the enhancement of the piezoelectricity of Ca-doped BaTiO $_{3}$ -based materials.

論文

Lattice dynamics of CH(NH $_{2}$ ) $_{2}$ PbI $_{3}$ and CH(NH $_{2}$ ) $_{2}$ SnI $_{3}$ investigated by inelastic X-ray scattering and comparison of their elastic properties

玉造博夢; 村上洋一*; 齋藤紀子*; 大橋直樹*; 筒井智嗣*

Physical Review B, 110(2), p.024301_1 - 024301_8, 2024/07

https://doi.org/10.1103/PhysRevB.110.024301

被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)

Using the inelastic X-ray scattering (IXS) technique, we investigate the lattice dynamics of inorganic-organic hybrid iodide perovskites FAPbI $_{3}$ and FASnI $_{3}$ (FA CH(NH $_{2}$ ) $_{2}$ , formamidinium) in their cubic phase and tetragonal phase. We find that the IXS spectra of FASnI $_{3}$ are highly broad at all momentum points, as has been widely observed in the Pb-based halide perovskites. The speeds of sound (phonon group velocities) and absolute values of elastic constants of FASnI $_{3}$ are smaller than those of FAPbI $_{3}$ in both phases. In addition, no significant difference in the phonon lifetimes of FAPbI $_{3}$ and FASnI $_{3}$ is observed. These results correlate better with the reported tendency that the lattice thermal conductivity of ASnX $_{3}$ is lower than that of APbX $_{3}$ . We discuss that our results also favor the up-conversion mechanism by acoustic phonons in the phonon bottleneck effect for the long lifetime of hot carriers.

論文

Investigation of the phonon dispersion associated with superlattice reflections in the BiS $_{2}$ -based superconductor LaBiS $_{2}$ O $_{0.5}$ F $_{0.5}$

玉造博夢; 長谷川巧*; 佐賀山基*; 水牧仁一朗*; 村上洋一*; 梶谷丈*; 東中隆二*; 松田達磨*; 青木勇二*; 筒井智嗣*

Physical Review B, 107(2), p.024303_1 - 024303_8, 2023/01

https://doi.org/10.1103/PhysRevB.107.024303

被引用回数：2 パーセンタイル：12.23(Materials Science, Multidisciplinary)

The phonon dispersion of a BiS $_{2}$ -based superconductor LaBiS $_{2}$ O $_{0.5}$ F $_{0.5}$ is investigated by first-principles calculations and inelastic X-ray scattering experiments. The origin of superlattice (SL) reflections arising from transverse-type lattice modulation, which were recently reported in [J. Kajitani ., J. Phys. Soc. Jpn. , 103601 (2021)], is discussed in terms of lattice dynamics. Our first-principles calculations of phonon dispersion and the Fermi surfaces (FSs) demonstrate that the phonon mode corresponding to the transverse-type lattice modulation is unstable, and the propagation vector corresponding to the SL reflections is close to the FS nesting vector, which suggests that the phonon softening originates from the FS nesting. Against these calculated expectations, measured phonon dispersion in LaBiS $_{2}$ O $_{0.5}$ F $_{0.5}$ along the Z-A direction, where the SL point is located, shows no remarkable temperature dependence, and there are no steeply declining branches accompanied with a softening around the SL point. Based on these results, we discuss the two possibilities for the transverse lattice modulation in LaBiS $_{2}$ O $_{0.5}$ F $_{0.5}$ : the order-disorder type structural transition and the displacive structural transition with an overdamped mode, for both of which the local structure distortion or the short range correlation within the BiS $_{2}$ plane would be essential.

論文

Phonon softening in Lu(Pt $_{1-x}$ Pd)In close to a zero-temperature structural instability

Gruner, T.*; Lucas, S.*; Geibel, C.*; 金子耕士; 筒井智嗣*; Schmalzl, K.*; Stockert, O.*

Physical Review B, 106(11), p.115142_1 - 115142_6, 2022/09

https://doi.org/10.1103/PhysRevB.106.115142

被引用回数：1 パーセンタイル：6.98(Materials Science, Multidisciplinary)

The disappearance of a charge-density-wave (CDW) transition in Lu(Pt $_{1-x}$ Pd)In is thought to be closely linked to a maximum of the superconducting transition temperature in the system. We studied the superstructure and the phonon softening in Lu(Pt $_{0.5}$ Pd $_{0.5}$ )In by means of neutron and high-resolution inelastic X-ray scattering. A full phonon softening at $q_{textrm{CDW}}$ = (0.5, 0.5, 0) with the appearance of superstructure peaks could be clearly identified. The large tail of the superstructure intensity above the CDW transition indicates the importance of critical fluctuations.

論文

Sm valence determination of Sm-based intermetallics using $^{149}$ Sm Mssbauer and Sm L $_{rm III}$ -edge X-ray absorption spectroscopies

筒井智嗣; 東中隆二*; 中村頼人*; 藤原孝将*; 中村仁*; 小林義男*; 伊藤孝; 依田芳卓*; 加藤和男*; 新田清文*; et al.

Hyperfine Interactions, 242(1), p.32_1 - 32_10, 2021/12

https://doi.org/10.1007/s10751-021-01759-x

被引用回数：1 パーセンタイル：75.14(Physics, Atomic, Molecular & Chemical)

$^{149}$ Sm synchrotron-radiation-based Mssbauer spectroscopy was performed in Sm-based intermetallics having a cubic crystal structure, Sm $_{3}Tr_{4}$ Ge $_{13}$ , SmB $_{6}$ , SmBe $_{13}$ , and Sm $Tr_{2}$ Al $_{20}$ ( = transition metals). In spite of the difference of the local structure around the Sm sites, the observed Mssbauer spectra consist of a single line at 300 K. On the other hand, Sm L $_{rm III}$ -edge X-ray absorption spectra consist of two components, suggesting Sm $^{2+}$ and Sm $^{3+}$ states. Difference of the number of the spectral components between the Mssbauer spectroscopy and X-ray absorption spectroscopy is caused by the difference of the time window in the scattering process of these measurements. Correlation between the isomer shifts in the Mssbauer spectroscopy and average Sm valence states estimated from the X-ray absorption spectroscopy exhibits a linear correlation.

論文

Lattice dynamics in CePdAl and LaPdAl

Doleal, P.*; Cejpek, P.*; 筒井智嗣*; 金子耕士; Legut, D.*; Carva, K.*; Javorsk, P.*

Scientific Reports (Internet), 11(1), p.20878_1 - 20878_10, 2021/10

https://doi.org/10.1038/s41598-021-99904-7

被引用回数：1 パーセンタイル：4.66(Multidisciplinary Sciences)

The interaction between phonons and 4f electrons, which is forming a new quantum state (quasi-bound state) beyond Born-Oppenheimer approximation, is very prominent and lattice dynamics plays here a key role. There is only a small number of compounds in which the experimental observation suggest such a scenario. One of these compounds is CePdAl. The inelastic X-ray scattering technique was used for mapping the phonon modes at X and Z points as well as in L and D directions, where the symmetry analysis of phonon modes was performed. The measured spectra are compared with the theoretical calculation, showing very good agreement. The results are discussed with respect to the magneto-elastic interaction. The phonon mode symmetry A1g was found to be unaffected by the interaction, which is in contrast to previous assumptions.

論文

Nature of structural instabilities in superconducting SrIrSn $_{13}$

金子耕士; Cheung, Y. W.*; Hu, Y.*; 今井正樹*; 谷奥泰明*; 金川響*; 村川譲一*; 森山広大*; Zhang, W.*; Lai, K. T.*; et al.

JPS Conference Proceedings (Internet), 30, p.011032_1 - 011032_6, 2020/03

https://doi.org/10.7566/JPSCP.30.011032

A quantum critical point appears as a second-order phase transition which takes place at zero temperature. In contrast to heavy-fermion systems in which magnetism often plays a vital role, recent studies revealed that structural instabilities can drive a system to a quantum critical point as well. In quasi-skutterudite (Ca,Sr)Sn $_{13}$ (=Rh, Ir), SrIrSn $_{13}$ exhibits superconductivity around $T_{rm sc}$ 5 K and a structural transition at $T^*{simeq}$ 147 K. Applying physical or chemical pressure on SrIrSn $_{13}$ suppresses rapidly, and a quasi-linear dependence of electrical resistivity, signature of non-Fermi liquid behavior, was observed where extrapolates to 0 K. The isomorphs (CaSr $_{1-x}$ )RhSn $_{13}$ exhibits similar behavior, where the criticality can be reached by 0.9 without external pressure. Neutron scattering experiments in SrIrSn $_{13}$ evidences the second order nature of the structural transition at by the observation of a continuous evolution of superlattice peak below and a gradual increase of critical scattering upon approaching to by cooling. Increase of in (CaSr $_{1-x}$ )RhSn $_{13}$ toward the quantum critical point leads to the systematic variation of the critical exponents of the order parameter. In addition, this substitution induces the phonon softening around the M point towards zero energy revealed by inelastic X-ray scattering experiment. We will present systematic variations in both elastic and inelastic channels upon approaching to the quantum critical point.

論文

Evidence of a structural quantum critical point in (CaSr $_{1-x}$ )RhSn $_{13}$ from a lattice dynamics study

Cheung, Y. W.*; Hu, Y. J.*; 今井正樹*; 谷奥泰明*; 金川響*; 村川譲一*; 森山広大*; Zhang, W.*; Lai, K. T.*; 吉村一良*; et al.

Physical Review B, 98(16), p.161103_1 - 161103_5, 2018/10

https://doi.org/10.1103/PhysRevB.98.161103

被引用回数：20 パーセンタイル：63.32(Materials Science, Multidisciplinary)

Approaching a quantum critical point has been an effective route to stabilize superconductivity. While the role of magnetic QCPs has been extensively discussed, similar exploration of a structural QCP is scarce. Using inelastic X-ray scattering, we examine the phonon spectrum of the nonmagnetic quasi-skutterudite (CaSr $_{1-x}$ )RhSn $_{13}$ , which represents a precious system to explore the interplay between structural instabilities and superconductivity by tuning the Ca concentration x. We unambiguously detect the softening of phonon modes around the M point on cooling towards the structural transition. Intriguingly, at x = 0:85, the soft mode energy squared at the M point extrapolates to zero at -5.7 K, providing the first compelling microscopic evidence of a structural QCP in (CaSr $_{1-x}$ )RhSn $_{13}$ . The enhanced phonon density-of-states at low energy provides the essential ingredient for realizing strong-coupling superconductivity near the structural QCP.

論文

Effect of -site randomness on the antiferroelectric/relaxor nature of the ground state; Diffuse and inelastic X-ray scattering study of Pb(In $_{1/2}$ Nb $_{1/2}$ )O

大和田謙二*; 塚田慎也*; 福田竜生; 筒井智嗣*; Baron, A. Q. R.*; 水木純一郎*; 大和英弘*; 安田直彦*; 寺内暉*

Physical Review B, 98(5), p.054106_1 - 054106_10, 2018/08

https://doi.org/10.1103/PhysRevB.98.054106

被引用回数：4 パーセンタイル：17.88(Materials Science, Multidisciplinary)

The effect of -site randomness on the antiferroelectric/relaxor nature of the ground state was investigated by studying diffuse and inelastic X-ray scattering from ordered and disordered Pb(In $_{1/2}$ Nb $_{1/2}$ )O (O- and D-PIN) single crystals. The diffuse scattering measurement of O-PIN (antiferroelectric at ) shows the existence of ferroelectrically interactive local polarization above . Inelastic X-ray scattering shows that the transverse-acoustic (TA) and transverse-optic (TO) modes are dominant at 800 K, while the central peak (CP) and TA modes are coupled and majorly contribute to the critical behavior of the diffuse scattering at . Upon these results, the -site randomness is discussed in terms of suppressing the antiferroelectric instability and enhancing the polarization fluctuation.

論文

Inelastic X-ray scattering of Al ( = La, Ce, = Cu, Au)

筒井智嗣*; 金子耕士; Pospisil, J.; 芳賀芳範

Physica B; Condensed Matter, 536, p.24 - 27, 2018/05

https://doi.org/10.1016/j.physb.2017.09.087

被引用回数：3 パーセンタイル：13.43(Physics, Condensed Matter)

Inelastic X-ray scattering (IXS) experiments of RTAl ( = La Ce, = Cu, Au) were carried out at 300 and 5.5 K. The spectra between LaCuAl and CeCuAl (LaAuAl and CeAuAl) are nearly identical at both temperatures except for temperature factors such as temperature dependence of Bose factor in IXS spectra and effect on thermal expansion. This means that no evident temperature dependence of IXS spectra was observed in CeTAl ( = Cu, Au).

論文

Second-order structural transition in (Ca $_{0.5}$ Sr $_{0.5}$ )RhSn $_{13}$

Cheung, Y. W.*; Hu, Y. J.*; Goh, S. K.*; 金子耕士; 筒井智嗣; Logg, P. W.*; Grosche, F. M.*; 金川響*; 谷奥泰明*; 今井正樹*; et al.

Journal of Physics; Conference Series, 807(3), p.032002_1 - 032002_4, 2017/04

BB2016-0329.pdf:0.86MB

https://doi.org/10.1088/1742-6596/807/3/032002

被引用回数：6 パーセンタイル：80.71(Physics, Condensed Matter)

(Ca $_{0.5}$ Sr $_{0.5}$ )RhSn $_{13}$ is a member of the substitution series (Ca $_{x}$ Sr $_{1-x}$ )RhSn $_{13}$ which has recently been argued to feature a structural quantum critical point at = 0.9. In the stoichiometric compound Sr $_{3}$ Rh $_{4}$ Sn $_{13}$ , the structural transition at 138 K has been shown to be a second-order phase transition. Moving towards xc, we examine the character of the structural transition in (Ca $_{0.5}$ Sr $_{0.5}$ )RhSn $_{13}$ (i.e. = 0.5, 55 K) using electrical resistivity, heat capacity and X-ray scattering. The absence of the thermal hysteresis in specific heat around , and the continuous evolution of the superlattice reflection detected by X-ray diffraction are consistent with the scenario that the structural transition associated with a modulation vector = (0.5, 0.5, 0) in (Ca $_{0.5}$ Sr $_{0.5}$ )RhSn $_{13}$ remains second-order on approaching the quantum critical point.

論文

Impurity effects in the microscopic elastic properties of polycrystalline Mg-Zn-Y alloys with a synchronised long-period stacking ordered phase

細川伸也*; 木村耕治*; 山崎倫昭*; 河村能人*; 吉田亨次*; 乾雅祝*; 筒井智嗣*; Baron, A. Q. R.*; 川北至信; 伊藤晋一*

Journal of Alloys and Compounds, 695, p.426 - 432, 2017/02

https://doi.org/10.1016/j.jallcom.2016.10.266

被引用回数：5 パーセンタイル：22.82(Chemistry, Physical)

Inelastic X-ray scattering (IXS) was performed on polycrystalline Mg $_{97}$ ZnY and Mg $_{85}$ ZnY alloys with synchronized long-period stacking ordered (LPSO) phase for investigating the impurity effects in the microscopic elastic properties. Inelastic neutron scattering (INS) was also carried out on the former alloy. LA modes were clearly observed in the IXS spectra of both the LPSO alloys, while TA modes can mainly be detected in the second Brillouin zone. Broader inelastic signals and larger quasielastic peaks are characteristic due to the phonon scattering by the Zn/Y impurities. Only the TA excitation energies increase by adding the impurities, which indicates a harder stiffness of the bond angles relating to the L1-type clusters in the LPSO alloys. New dispersion-less excitation modes are observed at about 10 meV by adding the Zn/Y impurities. By comparing with the INS data, the contributions of the impurities to these excitations are discussed using differences in the scattering cross-sections between neutrons and X-rays.

論文

Effect of magnetism on lattice dynamics in SrFeAs using high-resolution inelastic X-ray scattering

村井直樹*; 福田竜生; 小林達也*; 中島正道*; 内山裕士*; 石川大介*; 筒井智嗣*; 中村博樹; 町田昌彦; 宮坂茂樹*; et al.

Physical Review B, 93(2), p.020301_1 - 020301_5, 2016/01

https://doi.org/10.1103/PhysRevB.93.020301

被引用回数：7 パーセンタイル：31.36(Materials Science, Multidisciplinary)

Phonon spectra of detwinned SrFeAs crystals, as measured by inelastic X-ray scattering, show clear anisotropyaccompanying the magnetostructural transition at 200 K. We model the mode splitting using magnetic DFT calculations, including a phenomenological reduction in force-constant anisotropy that can be attributed to magnetic fluctuations. This serves as a starting point for a general model of phonons in this material applicable to both the antiferromagnetically ordered phase and the paramagnetic phase. Using this model, the measured splitting in the magnetic phase below T, and the measured phonon linewidth, we set a lower bound on the mean magnetic fluctuation frequency above T at 210 K.

論文

Mssbauer spectroscopy of actinide compounds

筒井智嗣

Mssbauer Effect Reference and Data Journal, 38(4), p.105 - 111, 2015/06

アクチノイド化合物のメスバウアー分光は日本でも海外でも実施可能な施設は限られる。日本におけるアクチノイドのメスバウアー分光の研究は1990年代に先端基礎研究センターにおいて開始された。本稿では、1996年に先端基礎研究センターで開始されたU-238メスバウアー分光及び東北大学金属材料研究所で開始されたネプツニウム金属間化合物のメスバウアー分光に関する研究成果について纏めた。また、これらのアクチノイドのメスバウアー分光の研究成果のレビューを行うとともに、その発展に寄与された故那須三郎阪大名誉教授の貢献に関してまとめたものである。

論文

X-ray absorption spectroscopy and novel electronic properties in heavy fermion compounds YbT $_{2}$ Zn $_{20}$ (T: Rh and Ir)

本多史憲*; 広瀬雄介*; 三宅厚志*; 水牧仁一朗*; 河村直己*; 筒井智嗣*; 綿貫徹; 渡辺真仁*; 竹内徹也*; 摂待力生*; et al.

Journal of Physics; Conference Series, 592(1), p.012021_1 - 012021_5, 2015/03

https://doi.org/10.1088/1742-6596/592/1/012021

被引用回数：3 パーセンタイル：69.88(Physics, Atomic, Molecular & Chemical)

重い電子系化合物YbT $_{2}$ Zn $_{20}$ (T: Rh and Ir)について、X線吸収分光法によりYb価数観察を行った。いずれの化合物でもYb価数は温度依存性を示し、約100K以下で冷却とともにYb価数が減少する変化が見られた。これは、同型化合物であるYbCo $_{2}$ Zn $_{20}$ において温度依存性が見られないこととは対照的な結果である。

論文

Anharmonic Pr guest modes in Pr(Os $_{1-x}$ Ru)Sb $_{12}$ investigated by inelastic X-ray scattering

筒井智嗣; 金子耕士; 宮崎亮一*; 東中隆二*; 青木勇二*; 小林理気*; 脇本秀一; Baron, A. Q. R.*; 菅原仁*; 佐藤英行*

JPS Conference Proceedings (Internet), 3, p.011060_1 - 011060_5, 2014/06

https://doi.org/10.7566/JPSCP.3.011060

We have investigated the Ru/Os concentration dependence of the Pr guest mode in Pr(Os $_{1-x}$ Ru)Sb $_{12}$ and its variation with temperature. The Pr guest mode at 3.2 meV in PrOsSb $_{12}$ at the N point linearly shifts to a higher energy with the substitution of Ru into the Os site. The energy of the Pr guest mode decreases with decreasing temperature for all compositions, indicating the presence of an anharmonic potential at the Pr site. The slope of the temperature dependence of the guest mode energy is steeper for pure PrOsSb $_{12}$ than for the other Pr(Os $_{1-x}$ Ru)Sb $_{12}$ compounds we measured. The present results imply the importance of the transition metal in determining anharmonicity in Pr(Os $_{1-x}$ Ru)Sb $_{12}$ .

論文

Multi-spin-state dynamics during insulator-metal crossover in LaCoO

土居篤典*; 藤岡淳*; 福田竜生; 筒井智嗣*; 奥山大輔*; 田口康二郎*; 有馬孝尚*; Baron, A. Q. R.*; 十倉好紀*

Physical Review B, 90(8), p.081109_1 - 081109_4, 2014/01

https://doi.org/10.1103/PhysRevB.90.081109

被引用回数：19 パーセンタイル：59.49(Materials Science, Multidisciplinary)

The phonon dynamics of spin-state crossover for perovskite LaCoO was investigated using infrared and inelastic X-ray spectroscopy. We observed that the Co-O bond stretching phonons couples to the thermally excited spin-state. The momentum dispersion of the optical mode is anomalously dispersionless (less than 3 meV), and this supports the spin-state disproportionation scenario. The steep enhancement of spin-state fluctuation compared to the charge gap suggests the density dependent spin state disproportionation; a simple low spin (LS)/high spin (HS)- or LS/intermediate spin (IS)-state disproportionation is realized at the initial stage with dilute HS- (or IS-) state density, while the complex spin-state disproportionation involving all of the LS-, IS- and HS-state is formed when the density of HS- (or IS-) state is enhanced.

論文

Temperature and magnetic field dependent Yb valence in YbRhSi observed by X-ray absorption spectroscopy

中井裕人*; 海老原孝雄*; 筒井智嗣*; 水牧仁一朗*; 河村直己*; 道村真司*; 稲見俊哉; 中村俊幸*; 近藤晃弘*; 金道浩一*; et al.

Journal of the Physical Society of Japan, 82(12), p.124712_1 - 124712_5, 2013/12

https://doi.org/10.7566/JPSJ.82.124712

被引用回数：9 パーセンタイル：52.19(Physics, Multidisciplinary)

重い電子化合物であるYbRhSiのYb価数の温度磁場依存性をX線吸収分光で観測した。測定からは、何れも突然の変化なしに、Yb価数が2Kから200Kの範囲で温度の下降に伴い減少することと、0Tから33Tの範囲で磁場の増加に伴い増加することが明かになった。Ybの価数は、磁場と温度に依存して、2.92から2.96の範囲であった。価数が2Kでは0Tで2.92で33Tで2.93である点で、YbRhSiは価数揺動状態にあることがわかり、高磁場でも整数価数に届かない。これらの結果はYbの価数が整数価数の3+に非常に近く、降温に伴い減少し、磁場の印加に伴い3+に近づくというこれまでの知識を支持するものである。