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Journal Articles

Contrasting magnetic structures in SrLaCuSbO$$_{6}$$ and SrLaCuNbO$$_{6}$$; Spin-$$frac{1}{2}$$ quasi-square-lattice $$J_{1}$$-$$J_{2}$$ Heisenberg antiferromagnets

Watanabe, Masari*; Kurita, Nubuyuki*; Tanaka, Hidekazu*; Ueno, Wataru*; Matsui, Kazuki*; Goto, Takayuki*; Hagihara, Masato

Physical Review B, 105(5), p.054414_1 - 054414_12, 2022/02

 Times Cited Count:2 Percentile:61.85(Materials Science, Multidisciplinary)

Journal Articles

Structures of magnetic excitations in the spin-$$frac{1}{2}$$ kagome-lattice antiferromagnets Cs$$_{2}$$Cu$$_{3}$$SnF$$_{12}$$ and Rb$$_{2}$$Cu$$_{3}$$SnF$$_{12}$$

Saito, Mutsuki*; Takagishi, Ryunosuke*; Kurita, Nubuyuki*; Watanabe, Masari*; Tanaka, Hidekazu*; Nomura, Ryuji*; Fukumoto, Yoshiyuki*; Ikeuchi, Kazuhiko*; Kajimoto, Ryoichi

Physical Review B, 105(6), p.064424_1 - 064424_15, 2022/02

 Times Cited Count:5 Percentile:69.66(Materials Science, Multidisciplinary)

Journal Articles

Magnons and spinons in Ba$$_{2}$$CoTeO$$_{6}$$; A Composite system of isolated spin-$$frac{1}{2}$$ triangular Heisenberg-like and frustrated honeycomb Ising-like antiferromagnets

Kojima, Yuki*; Kurita, Nubuyuki*; Tanaka, Hidekazu*; Nakajima, Kenji

Physical Review B, 105(2), p.L020408_1 - L020408_6, 2022/01

 Times Cited Count:2 Percentile:51.2(Materials Science, Multidisciplinary)

We report the neutron scattering results on magnetic orderings and excitations in Ba$$_{2}$$CoTeO$$_{6}$$ composed of two almost isolated subsystems A and B, which are described as an $${S = 1/2}$$ triangular Heisenberg-like antiferromagnet and a frustrated honeycomb Ising-like antiferromagnet, respectively. It was found that the excitation spectra of both subsystems are well separated and independent of each other. The excitation spectrum of subsystem A is composed of two single-magnon branches with roton-like minima at the M point and a clearly structured intense continuum, as similarly observed in Ba$$_{3}$$CoSb$$_{2}$$O$$_{9}$$, which is strongly indicative of spinon excitations. Dispersion curves for subsystem B can be described by linear spin wave theory within the third-neighbor exchange interaction.

Journal Articles

Localized magnetic excitations in the fully frustrated dimerized magnet Ba$$_{2}$$CoSi$$_{2}$$O$$_{6}$$Cl$$_{2}$$

Kurita, Nubuyuki*; Yamamoto, Daisuke*; Kanesaka, Takuya*; Furukawa, Nobuo*; Kawamura, Seiko; Nakajima, Kenji; Tanaka, Hidekazu*

Physical Review Letters, 123(2), p.027206_1 - 027206_6, 2019/07

 Times Cited Count:4 Percentile:37.12(Physics, Multidisciplinary)

Journal Articles

Triplon band splitting and topologically protected edge states in the dimerized antiferromagnet

Nawa, Kazuhiro*; Tanaka, Kimihito*; Kurita, Nubuyuki*; Sato, Taku*; Sugiyama, Haruki*; Uekusa, Hidehiro*; Kawamura, Seiko; Nakajima, Kenji; Tanaka, Hidekazu*

Nature Communications (Internet), 10, p.2096_1 - 2096_8, 2019/05

 Times Cited Count:15 Percentile:75(Multidisciplinary Sciences)

Search for topological materials has been actively promoted in the field of condensed matter physics for their potential application in energy-efficient information transmission and processing. Recent studies have revealed that topologically invariant states, such as edge states in topological insulators, can emerge not only in a fermionic electron system but also in a bosonic system, enabling nondissipative propagation of quasiparticles. Here we report the topologically nontrivial triplon bands measured by inelastic neutron scattering on the spin-1/2 two-dimensional dimerized antiferromagnet Ba$$_{2}$$CuSi$$_{2}$$O$$_{6}$$Cl$$_{2}$$. The excitation spectrum exhibits two triplon bands that are clearly separated by a band gap due to a small alternation in interdimer exchange interaction, consistent with a refined crystal structure. By analytically modeling the triplon dispersion, we show that Ba$$_{2}$$CuSi$$_{2}$$O$$_{6}$$Cl$$_{2}$$ is the first bosonic realization of the coupled Su-Schrieffer-Heeger model, where the presence of topologically protected edge states is prompted by a bipartite nature of the lattice.

Journal Articles

Structure of the magnetic excitations in the spin-1/2 triangular-lattice Heisenberg antiferromagnet Ba$$_{3}$$CoSb$$_{2}$$O$$_{9}$$

Ito, Saya*; Kurita, Nubuyuki*; Tanaka, Hidekazu*; Kawamura, Seiko; Nakajima, Kenji; Ito, Shinichi*; Kuwahara, Keitaro*; Kakurai, Kazuhisa*

Nature Communications (Internet), 8, p.235_1 - 235_6, 2017/08

 Times Cited Count:67 Percentile:93.85(Multidisciplinary Sciences)

Journal Articles

Delocalization of the $$f$$ electron in Ce$$_x$$La$$_{1-x}$$Ru$$_2$$Si$$_2$$; The de Haas-van Alphen effect measurement

Matsumoto, Yuji; Kimura, Noriaki*; Komatsubara, Takemi*; Aoki, Haruyoshi*; Kurita, Nubuyuki*; Terashima, Taichi*; Uji, Shinya*

Journal of Physics; Conference Series, 391, p.012042_1 - 012042_4, 2012/12

 Times Cited Count:1 Percentile:43.65

CeRu$$_2$$Si$$_2$$ is a paramagnetic heavy fermion compound with the electronic specific heat coefficient $$gamma$$ of 350 mJ/mol K$$^2$$. When a magnetic field is applied along the [001] direction of its tetragonal ThCr$$_2$$Si$$_2$$ structure, it exhibits metamagnetic transition at 7.7 T. On the other hand, when a magnetic field is applied in the (001) plane, metamagnetic transition does not occur. This magnetic anisotropy is maintained to lower Ce concentration samples. By replacing Ce with La, CeRu$$_2$$Si$$_2$$ changes to antiferromagnet at $$x_c$$ $$sim$$ 0.91 and finally to normal paramagnet of LaRu$$_2$$Si$$_2$$. In very low Ce concentration samples, the impurity Kondo effect is observed. The Kondo temperature of the $$x$$ = 0.02 sample is about 1 K. We have successfully observed all the dHvA oscillations in the dilute Ce concentration samples with fields in the (001) plane. Moreover, we have observed the variation of the dHvA oscillations with temperature crossing the Kondo temperature.

Journal Articles

Dilute La-substitutions in CeRhIn$$_5$$ studied by means of NMR/NQR techniques

Sakai, Hironori; Kurita, Nobuyuki*; Miclea, C. F.*; Movshovich, R.*; Lee, H.-O.*; Ronning, F.*; Bauer, E. D.*; Thompson, J. D.*

Journal of the Physical Society of Japan, 80(Suppl.A), p.SA059_1 - SA059_3, 2011/07

The effect of dilute La substitution in Ce$$_{1-x}$$La$$_{x}$$RhIn$$_{5}$$ (0$$le$$x$$le$$0.07) has been investigated microscopically by nuclear magnetic/quadrupole resonance (NMR/NQR). By the dilute La substitutions, the 4$$nu_{rm Q}$$ lines for In(1) sites are found to be undisturbed and to have a reasonably narrow width, even in the ordered AF state. These 4$$nu_{rm Q}$$ positions in the La-substituted CeRhIn$$_{5}$$ indicate a decrease of the internal field on In(1) sites, due to the reduction of hyperfine couplings by La substitutions. The spin-lattice relaxation rates ($$1/T_{1}$$) using these 4$$nu_{rm Q}$$ lines at high temperatures can be understood by the reduction of exchange energy and effective moments. On the other hand, $$1/T_{1}$$ in the AF ordered state can be explained by a gapped Fermi surface and spin fluctuations of uncompensated localized Ce moments near the La ions.

Oral presentation

Change of Fermi surface properties in dilute Ce concentration of Ce$$_x$$La$$_{1-x}$$Ru$$_2$$Si$$_2$$ system, 3

Matsumoto, Yuji; Kimura, Noriaki*; Komatsubara, Takemi*; Aoki, Haruyoshi*; Kurita, Nubuyuki*; Terashima, Taichi*; Uji, Shinya*

no journal, , 

We have performed the de Haas - van Alphen (dHvA) effect measurements in Ce$$_x$$La$$_{1-x}$$Ru$$_2$$Si$$_2$$ with magnetic fields in the (001) plane. All the oscillations corresponding to those in LaRu$$_2$$Si$$_2$$ can be observed in low Ce concentration samples and the evolution of the Fermi surface properties with x is found to depend strongly on the Fermi surface sheet. We will argue that the evolution can be attributed to anisotropic hybridization of the f electron with conduction electrons and resultant delocalization of the f electron.

Oral presentation

Elementary excitations in an S=1/2 antiferromagnetic chain KCuGaF$$_{6}$$

Tanaka, Hidekazu*; Kurita, Nubuyuki*; Umegaki, Izumi*; Ono, Toshio*; Laver, M.*; Niedermayer, Ch.*; R$"u$egg, Ch.*; Kawamura, Seiko; Nakajima, Kenji; Kakurai, Kazuhisa

no journal, , 

Oral presentation

Mizunami Underground Research Laboratory Project, Development of Engineering Technology for Underground Construction; Results and Evaluation for Post-excavation Grouting

Mikake, Shinichiro; Ikeda, Koki; Watanabe, Kazuhiko; Shiba, Nobuyuki; Kadoguchi, Yoshiaki; Tsuji, Masakuni*; Kusano, Takashi*; Kurita, Kazuaki*

no journal, , 

no abstracts in English

Oral presentation

Detail measurement on non-Kitaev term spin dynamics in $$alpha$$-RuCl$$_{3}$$

Nakajima, Kenji; Kojima, Yuki*; Kurita, Nubuyuki*; Tanaka, Hidekazu*

no journal, , 

Kitaev model is an exactly solvable model which has a quantum spin liquid state as the ground state. In Kitaev model, S=1/2 spins arranged on a honeycomb lattice are connected via three non-equivalent bonds with Ising-type interactions. $$alpha$$-RuCl$$_{3}$$ has been considered to be an excellent candidate of a Kitaev material. On the other hand, as a real material, the system has deviations from the ideal Kitaev model. The interaction between spins has non-Kitaev (Heisenberg) term as well as Kitaev one, which makes the exact ground state of $$alpha$$-RuCl$$_{3}$$ rather difficult to understand. We have studied spin dynamics in $$alpha$$-RuCl$$_{3}$$ by means of neutron scattering technique especially in low temperature and relatively lower energy range to obtained the detail picture of the ground state spin dynamics in this system, in which the non-Kitaev term highly contributes. Detail of our results and analysis will be shown in our presentation.

Oral presentation

Detail measurement on non-Kitaev term spin dynamics in $$alpha$$-RuCl$$_{3}$$ by using inelastic neutron scattering measurement

Nakajima, Kenji; Kojima, Yuki*; Kurita, Nubuyuki*; Tanaka, Hidekazu*

no journal, , 

Detail of magnetic excitations in the ground state of a honeycomb-lattice quantum magnet $$alpha$$-RuCl$$_{3}$$ was investigated by means of inelastic neutron scattering experiment.

Oral presentation

Magnons and spinons in Ba$$_{2}$$CoTeO$$_{6}$$; A Composite system of spin-1/2 triangular Heisenberg and honeycomb Ising antiferromagnets

Kojima, Yuki*; Kurita, Nubuyuki*; Tanaka, Hidekazu*; Nakajima, Kenji

no journal, , 

We report the neutron scattering results for magnetic orderings and excitations in Ba$$_{2}$$CoTeO$$_{6}$$ composed of two subsystems, A and B, which are described as an S = 1/2 triangular Heisenberg-like antiferromagnet and a frustrated honeycomb Ising-like antiferromagnet, respectively.

Oral presentation

Detail measurement on low temperature spin dynamics in $$S$$=1/2 honeycomb antiferromagnet, $$alpha$$-RuCl$$_{3}$$

Nakajima, Kenji; Kojima, Yuki*; Kurita, Nubuyuki*; Tanaka, Hidekazu*

no journal, , 

Detail of low energy magnetic excitations in the ground state of a honeycomb-lattice quantum magnet $$alpha$$-RuCl$$_{3}$$ was investigated by means of inelastic neutron scattering experiment. Temperature dependence of them were also investigated.

Oral presentation

Structured excitation continuum and short-range correlations in a spin-1/2 triangular lattice antiferromagnet $$mathrm{Ba_3CoSb_2O_9}$$

Kojima, Yuki*; Nakajima, Kenji; Kurita, Nubuyuki*; Tanaka, Hidekazu*; Kawamura, Seiko; Murai, Naoki

no journal, , 

no abstracts in English

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