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Journal Articles

Hybridization of Bogoliubov quasiparticles between adjacent CuO$$_2$$ layers in the triple-layer cuprate Bi$$_2$$Sr$$_2$$Ca$$_2$$Cu$$_3$$O$$_{10+delta}$$ studied by angle-resolved photoemission spectroscopy

Ideta, Shinichiro*; Johnston, S.*; Yoshida, Teppei*; Tanaka, Kiyohisa*; Mori, Michiyasu; Anzai, Hiroaki*; Ino, Akihiro*; Arita, Masashi*; Namatame, Hirofumi*; Taniguchi, Masaki*; et al.

Physical Review Letters, 127(21), p.217004_1 - 217004_6, 2021/11

Journal Articles

Absence of ferromagnetism in MnBi$$_2$$Te$$_4$$/Bi$$_2$$Te$$_3$$ down to 6 K

Fukasawa, Takuro*; Kusaka, Shotaro*; Sumida, Kazuki; Hashizume, Mizuki*; Ichinokura, Satoru*; Takeda, Yukiharu; Ideta, Shinichiro*; Tanaka, Kiyohisa*; Shimizu, Ryota*; Hitosugi, Taro*; et al.

Physical Review B, 103(20), p.205405_1 - 205405_6, 2021/05

 Times Cited Count:0 Percentile:0(Materials Science, Multidisciplinary)

Journal Articles

Fabrication of a novel magnetic topological heterostructure and temperature evolution of its massive Dirac cone

Hirahara, Toru*; Otrokov, M. M.*; Sasaki, Taisuke*; Sumida, Kazuki*; Tomohiro, Yuta*; Kusaka, Shotaro*; Okuyama, Yuma*; Ichinokura, Satoru*; Kobayashi, Masaki*; Takeda, Yukiharu; et al.

Nature Communications (Internet), 11, p.4821_1 - 4821_8, 2020/09

 Times Cited Count:11 Percentile:89.19(Multidisciplinary Sciences)

Journal Articles

Devil's staircase transition of the electronic structures in CeSb

Kuroda, Kenta*; Arai, Yosuke*; Rezaei, N.*; Kunisada, So*; Sakuragi, Shunsuke*; Alaei, M.*; Kinoshita, Yuto*; Bareille, C.*; Noguchi, Ryo*; Nakayama, Mitsuhiro*; et al.

Nature Communications (Internet), 11, p.2888_1 - 2888_9, 2020/06

 Times Cited Count:3 Percentile:42.38(Multidisciplinary Sciences)

Journal Articles

Experimental investigation of the suppressed superconducting gap and double-resonance mode in Ba$$_{1-x}$$K$$_{x}$$Fe$$_{2}$$As$$_{2}$$

Ideta, Shinichiro*; Murai, Naoki; Nakajima, Masamichi*; Kajimoto, Ryoichi; Tanaka, Kiyohisa*

Physical Review B, 100(23), p.235135_1 - 235135_7, 2019/12

 Times Cited Count:0 Percentile:0(Materials Science, Multidisciplinary)

Journal Articles

Effect of electron correlations on spin excitation bandwidth in Ba$$_{0.75}$$K$$_{0.25}$$Fe$$_{2}$$As$$_{2}$$ as seen via time-of-flight inelastic neutron scattering

Murai, Naoki; Suzuki, Katsuhiro*; Ideta, Shinichiro*; Nakajima, Masamichi*; Tanaka, Kiyohisa*; Ikeda, Hiroaki*; Kajimoto, Ryoichi

Physical Review B, 97(24), p.241112_1 - 241112_6, 2018/06

 Times Cited Count:5 Percentile:39.54(Materials Science, Multidisciplinary)

We use inelastic neutron scattering (INS) to investigate the effect of electron correlations on spin dynamics in iron-based superconductor Ba$$_{0.75}$$K$$_{0.25}$$Fe$$_{2}$$As$$_{2}$$. Our INS data show a spin-wave-like dispersive feature, with a zone boundary energy of 200 meV. A first principles analysis of dynamical spin susceptibility, incorporating the mass renormalization factor of 3, as determined by angle-resolved photoemission spectroscopy, provides a reasonable description of the observed spin excitations. This analysis shows that electron correlations in the Fe-3d bands yield enhanced effective electron masses, and consequently, induce substantial narrowing of the spin excitation bandwidth. Our results highlight the importance of electron correlations in an itinerant description of the spin excitations in iron-based superconductors.

Journal Articles

Angle-resolved photoemission spectroscopy study of PrFeAsO$$_{0.7}$$; Comparison with LaFePO

Nishi, Ichiro*; Ishikado, Motoyuki; Ideta, Shinichiro*; Malaeb, W.*; Yoshida, Teppei*; Fujimori, Atsushi*; Kotani, Yoshinori*; Kubota, Masato*; Ono, Kanta*; Yi, M.*; et al.

Physical Review B, 84(1), p.014504_1 - 014504_5, 2011/07

 Times Cited Count:20 Percentile:66.65(Materials Science, Multidisciplinary)

We have performed an angle-resolved photoemission spectroscopy (ARPES) study of the iron-based superconductor PrFeAsO$$_{0.7}$$ and examined the Fermi surfaces and band dispersions near the fermi level. Heavily hole-doped electronic states have been observed due to the polar nature of the cleaved surfaces. Nevertheless, we have found that the ARPES spectra basically agree with band dispersions calculated in the local density approximation (LDA) if the bandwidth is reduced by a factor of $$sim$$ 2.5 and then the chemical potential is lowered by $$sim$$ 70 meV. Comparison with previous ARPES results on LaFePO reveals that the energy positions of the $$d$$$$_{3z^{2}-r^{2}}$$- and $$d$$$$_{yz,zx}$$-derived bands are considerably different between the two materials, which we attribute to the different pnictogen height as predicted by the LDA calculation.

Oral presentation

Two distinct resonance-like excitations in underdoped Ba_${1-x}$K_${x}$Fe_${2}$As_${2}$ (x = 0.25) as seen via inelastic neutron scattering

Murai, Naoki; Kajimoto, Ryoichi; Ikeuchi, Kazuhiko*; Tanaka, Kiyohisa*; Nakajima, Masamichi*; Ideta, Shinichiro*; Suzuki, Katsuhiro*

no journal, , 

We report an inelastic neutron scattering (INS) study of underdoped Ba_${1-x}$K_${x}$Fe_${2}$As_${2}$ that shows the presence of double-resonance at the same commensurate wave vector in the superconducting (SC) state. By comparing our INS data with the SC gap structure of the same crystal, as measured by angle-resolved photoemission spectroscopy (ARPES), we show that the observed double-resonance feature originates neither from SC gap anisotropy nor from multiple SC gaps on different Fermi-surface sheets. This suggests that the double-resonance feature in iron-pnictides cannot be interpreted within a spin-exciton scenario.

Oral presentation

Large downward renormalization of spin excitation energies in Ba$$_{0.75}$$K$$_{0.25}$$Fe$$_{2}$$As$$_{2}$$ due to electron correlation effects

Murai, Naoki; Kajimoto, Ryoichi; Suzuki, Katsuhiro*; Ideta, Shinichiro*; Nakajima, Masamichi*; Ikeda, Hiroaki*; Tanaka, Kiyohisa*

no journal, , 

Using inelastic neutron scattering (INS) and angle-resolved photoemission spectroscopy (ARPES), we investigate the spin dynamics of iron-based superconductor Ba$$_{0.75}$$K$$_{0.25}$$Fe$$_{2}$$As$$_{2}$$. The INS data show a spin-wave-like dispersive feature, with a zone boundary energy of 200 meV. A random phase approximation (RPA) treatment of the dynamical spin susceptibility, incorporating the band renormalization factor of 3 derived from the ARPES measurements on the same crystals, provides a reasonable description of the observed spin excitations. This analysis shows that the experimental spin excitation peak lies at a much lower energy than the bare value, reflecting a strong renormalization of the quasiparticle band dispersion near the Fermi level due to electron correlation effect. The present results point to a unified framework that connects the magnetic response to the underlying electronic structure of the materials.

Oral presentation

Large downward renormalization of spin excitation energies in Ba$$_{1-x}$$K$$_{x}$$Fe$$_{2}$$As$$_{2}$$ due to electron correlation effects

Murai, Naoki; Kajimoto, Ryoichi; Suzuki, Katsuhiro*; Ikeda, Hiroaki*; Nakajima, Masamichi*; Ideta, Shinichiro*; Tanaka, Kiyohisa*

no journal, , 

no abstracts in English

Oral presentation

Large downward renormalization of spin excitation energies in Ba$$_{0.75}$$K$$_{0.25}$$Fe$$_{2}$$As$$_{2}$$ due to electron correlation effects

Murai, Naoki; Kajimoto, Ryoichi; Suzuki, Katsuhiro*; Nakajima, Masamichi*; Ikeda, Hiroaki*; Ideta, Shinichiro*; Tanaka, Kiyohisa*

no journal, , 

We report inelastic neutron scattering (INS) study of hole-doped iron-based superconductor Ba$$_{1-x}$$K$$_{x}$$Fe$$_{2}$$As$$_{2}$$ (x = 0.25). The INS data show a spin-wave-like dispersive feature, with a zone boundary energy of 200 meV. A random phase approximation (RPA) treatment of the dynamical spin susceptibility, incorporating the band renormalization factor of 3 derived from angle-resolved photoemission spectroscopy (ARPES) measurements on the same sample, provides a reasonable description of the observed spin excitations. This analysis shows that the Fe-3d bandwidth narrowing due to electron correlation is directly reflected in the spin excitation energy scale. We will discuss the current state of our analysis relating the magnetic response to the underlying electronic structure of the materials.

Oral presentation

Effect of electron correlations on spin excitation bandwidth in Ba$$_{0.75}$$K$$_{0.25}$$Fe$$_{2}$$As$$_{2}$$ as seen via time-of-flight inelastic neutron scattering

Murai, Naoki; Kajimoto, Ryoichi; Suzuki, Katsuhiro*; Ikeda, Hiroaki*; Nakajima, Masamichi*; Ideta, Shinichiro*; Tanaka, Kiyohisa*

no journal, , 

We use inelastic neutron scattering (INS) to investigate the effect of electron correlations on spin dynamics in iron-based superconductor Ba$$_{0.75}$$K$$_{0.25}$$Fe$$_{2}$$As$$_{2}$$. Our INS data show a spin-wave-like dispersive feature, with a zone boundary energy of 200 meV. A first principles analysis of dynamical spin susceptibility, incorporating the mass renormalization factor of 3, as determined by angle-resolved photoemission spectroscopy, provides a reasonable description of the observed spin excitations. This analysis shows that electron correlations in the Fe-3d bands yield enhanced effective electron masses, and consequently, induce substantial narrowing of the spin excitation bandwidth. Our results highlight the importance of electron correlations in an itinerant description of the spin excitations in iron-based superconductors.

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