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Journal Articles

Retreat from stress; Rattling in a planar coordination

Suekuni, Koichiro*; Lee, C. H.*; Tanaka, Hiromi*; Nishibori, Eiji*; Nakamura, Atsushi*; Kasai, Hidetaka*; Mori, Hitoshi*; Usui, Hidetomo*; Ochi, Masayuki*; Hasegawa, Takumi*; et al.

Advanced Materials, 30(13), p.1706230_1 - 1706230_6, 2018/03

 Times Cited Count:35 Percentile:90.91(Chemistry, Multidisciplinary)

Thermoelectric materials for highly efficient devices must satisfy conflicting requirements of high electrical conductivity and low thermal conductivity. In this paper, we studied the crystal structure and phonon dynamics of tetrahedrites (Cu,Zn)$$_{12}$$(Sb,As)$$_{4}$$S$$_{13}$$. The results revealed that the Cu atoms in a planar coordination are rattling, which effectively scatter phonons. These findings provide a new strategy for the development of highly efficient thermoelectric materials with planar coordination.

Journal Articles

First-principles study of antimony doping effects on the iron-based superconductor CaFe(Sb$$_{x}$$As$$_{1-x}$$)$$_{2}$$

Nagai, Yuki; Nakamura, Hiroki; Machida, Masahiko; Kuroki, Kazuhiko*

Journal of the Physical Society of Japan, 84(9), p.093702_1 - 093702_4, 2015/09

 Times Cited Count:6 Percentile:50.68(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Switching of intra-orbital spin excitations in electron-doped iron pnictide superconductors

Iimura, Soshi*; Matsuishi, Satoru*; Miyakawa, Masashi*; Taniguchi, Takashi*; Suzuki, Katsuhiro*; Usui, Hidetomo*; Kuroki, Kazuhiko*; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; et al.

Physical Review B, 88(6), p.060501_1 - 060501_5, 2013/08

 Times Cited Count:26 Percentile:76.11(Materials Science, Multidisciplinary)

Journal Articles

$$Q$$-scan analysis of the neutron scattering in iron-based superconductors

Nagai, Yuki; Kuroki, Kazuhiko*

Physical Review B, 85(13), p.134521_1 - 134521_7, 2012/04

 Times Cited Count:5 Percentile:26.63(Materials Science, Multidisciplinary)

We propose a way to determine the pairing state of the iron pnictide superconductors exploiting the momentum ($$Q$$) scan of the neutron scattering data. We investigate the spin susceptibility in the $$s$$$$pm$$ and $$s$$$$_{++}$$ superconducting states for various doping levels using the effective five-orbital model and considering the quasiparticle damping. The peak position of the intensity shifts from the position on the line $$Q$$$$_{x}$$ = $$pi$$ to that on the line $$Q$$$$_{y}$$ = 0 as the doping level is decreased from electron doping to hole doping. We find that the $$Q$$ dependence of the ratio of the intensity in the superconducting state to that in the normal state is qualitatively different between the $$s$$$$pm$$-wave and $$s$$$$_{++}$$-wave pairings. We propose to investigate experimentally this ratio in $$Q$$ space to distinguish the two pairing states.

Journal Articles

Theoretical analysis for inelastic neutron scattering on BaFe$$_{2}$$(As$$_{1-x}$$,P$$_{x}$$)$$_{2}$$ using realistic three-dimensional 10-orbital tight-binding model

Nagai, Yuki; Nakamura, Hiroki; Suzuki, Katsuhiro*; Usui, Hidetomo*; Kuroki, Kazuhiko*; Machida, Masahiko

Journal of the Physical Society of Japan, 80(Suppl.B), p.SB021_1 - SB021_4, 2011/12

 Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)

We calculate spin susceptibility on the basis of the multi-orbital random-phase approximation with use of the realistic three-dimensional 10-orbital tight-binding model for an iron-based superconductor BaFe$$_{2}$$(As$$_{1-x}$$,P$$_{x}$$)$$_{2}$$ which seems to have gap-nodes. We show that the shape of nodes on the Fermi surface for BaFe$$_{2}$$(As$$_{1-x}$$,P$$_{x}$$)$$_{2}$$ is distinguishable according to inelastic neutron scattering experiments. Our results are consistent with the recent neutron scattering experiments for BaFe$$_{2}$$(As$$_{1-x}$$,P$$_{x}$$)$$_{2}$$ with Tc = 30 K.

Journal Articles

$$s_{pm}$$-like spin resonance in the iron-based nodal superconductor BaFe$$_2$$(As$$_{0.65}$$P$$_{0.35}$$)$$_2$$ observed using inelastic neutron scattering

Ishikado, Motoyuki; Nagai, Yuki; Kodama, Katsuaki; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Wakimoto, Shuichi; Nakamura, Hiroki; Machida, Masahiko; Suzuki, Katsuhiro*; et al.

Physical Review B, 84(14), p.144517_1 - 144517_5, 2011/10

 Times Cited Count:26 Percentile:74.17(Materials Science, Multidisciplinary)

We performed inelastic neutron scattering on a powder sample of iron-based superconductor BaFe$$_2$$(As$$_{0.65}$$P$$_{0.35}$$)$$_2$$ with $$T_c$$ = 30 K. Although this system is expected to have line nodes in its superconducting order parameter, we have observed spin resonance at the same scattering vector as that appeared in the $$s_{pm}$$-wave iron-based superconductors without line nodes. Moreover, the resonance enhancement, which can be a measure of the area of sign reversal between the hole and electron Fermi surfaces (FSs), is comparable to those without line nodes. These facts indicate that the sign reversal between the FSs is still dominant in this system, and the line nodes should create only limited area of sign-reversal on a single FS. Hence the system can hold higher Tc than the other iron-based superconductors with nodal symmetry, such as LaFePO$$_{1-y}$$ and KFe$$_2$$As$$_2$$ ($$T_c <$$ 10 K).

Journal Articles

Determination of the pairing state in iron-based superconductors through neutron scattering

Nagai, Yuki; Kuroki, Kazuhiko*

Physical Review B, 83(22), p.220516_1 - 220516_4, 2011/06

 Times Cited Count:14 Percentile:55.3(Materials Science, Multidisciplinary)

We calculate the spin susceptibility in the $$s_pm$$ and $$s_{++}$$ superconducting states of the iron pnictides using the effective five orbital model and considering the quasiparticle damping. For the experimentally evaluated magnitude of the quasiparticle damping and the superconducting gap, the results at the wave vector $$simeq(pi,0)$$ show that the $$s_pm$$ state is more consistent with the neutron scattering experiments, while for larger quasiparticle damping and the superconducting gap, the $$s_{++}$$ state can be more consistent. To distinguish between two cases that reproduce the experiments at the wave vector $$simeq(pi,0)$$, we propose to investigate experimentally the wave vector $$simeq(pi,pi)$$.

Journal Articles

Distinct structural requirements for interleukin-4 (IL-4) and IL-13 binding to the shared IL-13 receptor facilitate cellular tuning of cytokine responsiveness

Ito, Takachika*; Suzuki, Shoichi*; Kanaji, Sachiko*; Shiraishi, Hiroshi*; Ota, Shoichiro*; Arima, Kazuhiko*; Tanaka, Go*; Tamada, Taro; Honjo, Eijiro*; Garcia, K. C.*; et al.

Journal of Biological Chemistry, 284(36), p.24289 - 24296, 2009/09

 Times Cited Count:21 Percentile:46.03(Biochemistry & Molecular Biology)

Both IL-4 and IL-13 can bind to the shared receptor composed of the IL-4 receptor $$alpha$$ chain and the IL-13 receptor $$alpha$$-1 chain (IL-13R$$alpha$$1); however, the assembly mechanisms of these ligands to the receptor is different, enabling the principal functions of these ligands to be different. We have previously shown that the N-terminal Ig-like domain in IL-13R$$alpha$$1, called the D1 domain, is the specific and critical binding unit for IL-13. However, it has still remained obscure which the amino acid has specific binding capacity to IL-13 and why the D1 domain acts as the binding site for IL-13, but not IL-4. To address these questions, in this study, we performed the mutational analyses for the D1 domain, combining the structural data to identify the amino acids critical for binding to IL-13. Mutations of Lys76, Lys77, or Ile78 in c' strand in which the crystal structure showed interact with IL-13 and those of Trp65 and Ala79 adjacent to the interacting site, resulted in significant impairment of IL-13 binding, demonstrating that these amino acids generate the binding site. Furthermore, mutations of Val35, Leu38, or Val42 at N-terminal $$beta$$-strand also resulted in loss of IL-13 binding, probably from decrease structural stability. None of the mutations employed here affected IL-4 binding. These results demonstrate that the hydrophobic patch composed of Lys76, Lys77, and Ile78 is the IL-13 recognition site and solidify our understanding that the differential requirements of the D1 domain in IL-13R$$alpha$$1 allows the shared receptor to respond differentially to IL-4 and IL-13.

Journal Articles

Expression of the extracellular region of the human interleukin-4 receptor $$alpha$$ chain and interleukin-13 receptor $$alpha$$1 chain by a silkworm-baculovirus system

Honjo, Eijiro; Shoyama, Yoshinari; Tamada, Taro; Shigematsu, Hideki*; Hatanaka, Takaaki*; Kanaji, Sachiko*; Arima, Kazuhiko*; Ito, Yuji*; Izuhara, Kenji*; Kuroki, Ryota

Protein Expression and Purification, 60(1), p.25 - 30, 2008/07

 Times Cited Count:13 Percentile:36.52(Biochemical Research Methods)

The receptor binding to Interleukin (IL)-13 is composed of the IL-13 receptor $$alpha$$1 chain (IL-13R $$alpha$$1) and the IL-4 receptor $$alpha$$ chain (IL-4R $$alpha$$). In order to investigate the interaction of IL-13 with IL-13R $$alpha$$1 and IL-4R $$alpha$$, the DNA fragments coding the extracellular regions of human IL-13R $$alpha$$1 and the IL-4R $$alpha$$ were fused with mouse Fc and expressed by a silkworm-baculovirus system. The expressed receptors were successfully purified by affinity chromatography using protein A, and the Fc region was removed by thrombin digestion. Size exclusion chromatography and SPR analysis revealed that mixture of IL-13 and IL-13R$$alpha$$1 showed predominant affinity to IL-4R$$alpha$$, although neither detectable affinity of IL-13 nor IL-13R$$alpha$$1 was observed against IL-4R$$alpha$$. Combining these data with the moderate affinity of IL-13 to IL-13R$$alpha$$1, this indicates that IL-13 first binds to IL-13R$$alpha$$1 and recruits consequently to IL-4R.

Oral presentation

Expression and purification of extracellular region of interleukin-13 receptor $$alpha$$1 chain and its interaction with its ligand

Kuroki, Ryota; Honjo, Eijiro; Tamada, Taro; Arima, Kazuhiko*; Izuhara, Kenji*

no journal, , 

Interleukin-13 (IL-13) interacts with two types of receptors, the IL-13R$$alpha$$1 chain (IL-13R$$alpha$$1) and the IL-4R$$alpha$$ chain (IL-4R$$alpha$$), that transduce the IL-13 signals. In order to investigate the interaction of IL-13 with IL-13R$$alpha$$1 and IL-4R$$alpha$$, the genes coding the extracellular regions of human IL-13R$$alpha$$1 and the IL-4R$$alpha$$ containing cytokine receptor homologous region (CRH), were fused with human Fc, and expressed by silk worm. After further purification with anion-exchange chromatography, the receptors were used to investigate the ligand-receptor interaction. The size exclusion chromatography showed that association between IL-13 and IL-13Ra1 could not be observed in this condition whereas the clear association of IL-13 and IL-13Ra1 was observed after adding IL-4R$$alpha$$. It indicates that the association between IL-13 and IL-4R$$alpha$$ increase the IL-13 affinity to IL-13R$$alpha$$1.

Oral presentation

Preparation and characterization of extracelluar region of Interleukin-13 receptor $$alpha$$1 chain and IL-4 receptor $$alpha$$

Honjo, Eijiro; Shoyama, Yoshinari; Tamada, Taro; Arima, Kazuhiko*; Kanaji, Sachiko*; Izuhara, Kenji*; Kuroki, Ryota

no journal, , 

The receptor binding to Interleukin (IL)-13 is composed of the IL-13 receptor $$alpha$$1 chain (IL-13R$$alpha$$1) and the IL-4 receptor $$alpha$$ chain (IL-4R$$alpha$$). In order to investigate the interaction of IL-13 with IL-13R$$alpha$$1 and IL-4R$$alpha$$, the DNA fragments coding the extracellular regions of human IL-13R$$alpha$$1 and the IL-4R$$alpha$$, containing a cytokine receptor homologous region, were fused with human Fc and expressed by silkworm-baculovirus system. Size exclusion chromatography did not reveal association between IL-13 and IL-13R$$alpha$$1 under these conditions, but the clear association of IL-13 and IL-13R$$alpha$$1 was observed after adding IL-4R$$alpha$$. This indicates that both extracellular regions of IL-13R$$alpha$$1 and IL-4R$$alpha$$ have functions, and the association between IL-13 and IL-4R$$alpha$$ increases the IL-13 affinity to IL-13R$$alpha$$1.

Oral presentation

Impurity effect in multi-orbital, sign-reversing s-wave superconductors

Nagai, Yuki; Kuroki, Kazuhiko*; Machida, Masahiko; Aoki, Hideo*

no journal, , 

no abstracts in English

Oral presentation

Neutron scattering resonance as a probe for determining the pairing state in iron pnictide superconductor

Nagai, Yuki; Kuroki, Kazuhiko*

no journal, , 

no abstracts in English

Oral presentation

Inelastic neutron scattering on iron-based superconductors

Ishikado, Motoyuki; Nagai, Yuki; Kodama, Katsuaki; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Mizuno, Fumio; Wakimoto, Shuichi; Nakamura, Hiroki; Machida, Masahiko; et al.

no journal, , 

Three years have passed since the discovery of iron-based superconductors, its maximum superconducting transition temperature ($$T_c$$) is 55 K, resulting in second highest material system next to cuprate high-$$T_c$$ superconductors. Among various material systems in iron-based superconductors, we have systematically studied on LaFeAsO$$_{1-x}$$F$$_x$$ ($$T_c^{max}$$=28 K) of first discovered system and BaFe$$_2$$(As,P)$$_2$$ which have recently attracted tremendous attention by the discovery of line nodes in its order parameter. In the session, we present recent results on "spin fluctuation and superconductivity on LaFePO$$_{0.9}$$", and "symmetry of order parameter on BaFe$$_2$$(As,P)$$_2$$ by inelastic neutron scattering" studied by the chopper spectrometer 4SEASONS (J-PARC).

Oral presentation

Resonant spin excitation on iron-based superconductor BaFe$$_2$$(As,P)$$_2$$

Ishikado, Motoyuki; Nagai, Yuki; Kodama, Katsuaki; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Wakimoto, Shuichi; Nakamura, Hiroki; Machida, Masahiko; Suzuki, Katsuhiro*; et al.

no journal, , 

In this study, we have performed inelastic neutron scattering measurement on 36g powder sample of optimally-doped BaFe$$_2$$(As,P)$$_2$$ whose superconducting order parameter is expected to have line node by Fermi chopper spectrometer 4SEASONS in J-PARC. Unexpectedly, we have observed spin resonance at same $$Q$$-position and nearly identical resonance enhancement ration to other iron-based superconducctors with fully-gapped $$s_{+-}$$-wave. We will discuss about the possible superconducting gap symmetry based on our experimental results.

Oral presentation

Inelastic neutron scattering studies on iron-based high-$$T_c$$ superconductors

Ishikado, Motoyuki; Kodama, Katsuaki; Wakimoto, Shuichi; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Mizuno, Fumio; Nagai, Yuki; Nakamura, Hiroki; Machida, Masahiko; et al.

no journal, , 

Among various iron-based superconductors, we have systematically studied on LaFeAsO$$_{1-x}$$F$$_x$$ ($$T_c^{max}$$=28 K) and BaFe$$_2$$(As,P)$$_2$$ ($$T_c^{max}$$=31 K) by the Fermi chopper spectrometer 4SEASONS (J-PARC). We will discuss the possible relation between high-$$T_c$$ superconductivity and magnetic fluctuation based on our inelastic neutron scattering results.

Oral presentation

Spin resonance on Fe-based superconductor BaFe$$_2$$(As,P)$$_2$$ with nodal gap symmetry

Ishikado, Motoyuki; Kodama, Katsuaki; Wakimoto, Shuichi; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Nagai, Yuki; Nakamura, Hiroki; Machida, Masahiko; Suzuki, Katsuhiro*; et al.

no journal, , 

In this study, we performed inelastic neutron scattering measurement on 36g polycrystalline powder sample of optimally-doped BaFe$$_2$$(As$$_{0.65}$$P$$_{0.35}$$)$$_2$$ using a Fermi chopper spectrometer 4SEASONS in J-PARC. We observed strong spin resonance at the same $$Q$$-position similar to those of other iron-based superconductors with fully-gapped $$s_{pm}$$-wave. We will discuss about the possible superconducting gap symmetry and what causes relatively high-$$T_{rm c}$$ of this material based on our inelastic neutron scattering results.

Oral presentation

Neutron scattering as a probe for determining the pairing state in iron pnictide superconductors

Nagai, Yuki; Kuroki, Kazuhiko*

no journal, , 

no abstracts in English

Oral presentation

Magnetic scattering on Fe-based superconductors La1111 and BaFe$$_2$$(As,P)$$_2$$

Ishikado, Motoyuki; Nagai, Yuki; Kodama, Katsuaki; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Mizuno, Fumio; Wakimoto, Shuichi; Nakamura, Hiroki; Machida, Masahiko; et al.

no journal, , 

We report systematic studies on Fe-based superconductors LaFeAsO$$_{1-x}$$F$$_x$$ ($$T^{max}_{rm c}$$ =28 K) and BaFe$$_2$$(As,P)$$_2$$ ($$T^{max}_{rm c}$$ =31 K) by using inelastic neutron scattering measurement.

Oral presentation

Spin resonance mode on Fe-based superconductor BaFe$$_2$$(As,P)$$_2$$ with $$T_{rm c}$$=30K

Ishikado, Motoyuki; Nagai, Yuki; Kodama, Katsuaki; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Wakimoto, Shuichi; Nakamura, Hiroki; Machida, Masahiko; Suzuki, Katsuhiro*; et al.

no journal, , 

In this study, we performed inelastic neutron scattering measurement on 36g polycrystalline powder sample of optimally-doped BaFe$$_2$$(As$$_{0.65}$$,P$$_{0.35}$$)$$_2$$ using Fermi chopper spectrometer 4SEASONS in J-PARC. Unexpectedly, we observed spin resonance at the same $$Q$$-position and nearly identical resonance enhancement ratio to other iron-based superconductors with fully-gapped $$s_{pm}$$-wave. We will discuss about the possible superconducting gap symmetry based on our inelastic neutron scattering experiment and theoretical calculations.

24 (Records 1-20 displayed on this page)