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Journal Articles

Spin gap in the weakly interacting quantum spin chain antiferromagnet KCuPO$$_{4}$$$$cdot$$H$$_{2}$$O

Fujihara, Masayoshi; Hagihara, Masato; Morita, Katsuhiro*; Murai, Naoki; Koda, Akihiro*; Okabe, Hirotaka*; Mitsuda, Setsuo*

Physical Review B, 107(5), p.054435_1 - 054435_8, 2023/02

https://doi.org/10.1103/PhysRevB.107.054435
 Times Cited Count：0 Percentile：0(Materials Science, Multidisciplinary)

The $$S$$ = 1/2 Heisenberg linear chain antiferromagnet is the simplest spin model; nevertheless it serves as a platform for various quantum many-body phenomena. Here, we report the magnetic behavior of a quasi-one-dimensional antiferromagnet KCuPO$$_{4}$$$$cdot$$H$$_{2}$$O. A long-range commensurate antiferromagnetic order with ordered moment 0.31(1) $$mu_{rm{B}}$$ per spin occurs at $$T_{rm{N}}$$ = 11.7(1) K. Above $$T_{rm{N}}$$, the inelastic neutron excitation is characterized by a two spinon continuum. The intrachain interaction $$J$$ and interchain interaction $$|J'|$$ are estimated to be 172 K and 4.25(4) K, respectively; thus the ratio of the $$|J'|$$/$$J$$ = 0.0247(3). At lower energies, below $$T_{rm{N}}$$, a spin gap is observed in the dispersive excitations. These results are consistent with characteristics observed in weakly interacting $$S$$ = 1/2 Heisenberg chain system.

Journal Articles

Birchite Cd$$_{2}$$Cu$$_{2}$$(PO$$_{4}$$)$$_{2}$$SO$$_{4}$$ $$cdot$$ 5H$$_{2}$$O as a model antiferromagnetic spin-1/2 Heisenberg $${it J}$$$$_{1}$$-$${it J}$$$$_{2}$$ chain

Fujihara, Masayoshi; Jeschke, H. O.*; Morita, Katsuhiro*; Kuwai, Tomohiko*; Koda, Akihiro*; Okabe, Hirotaka*; Matsuo, Akira*; Kindo, Koichi*; Mitsuda, Setsuo*

Physical Review Materials (Internet), 6(11), p.114408_1 - 114408_8, 2022/11

https://doi.org/10.1103/PhysRevMaterials.6.114408
 Times Cited Count：0 Percentile：0(Materials Science, Multidisciplinary)

$${it S}$$ = 1/2 Heisenberg $${it J}$$$$_{1}$$-$${it J}$$$$_{2}$$ chain antiferromagnets have been investigated extensively due to their exotic magnetic states. Here, we report the magnetic behavior of birchite Cd$$_{2}$$Cu$$_{2}$$(PO$$_{4}$$)$$_{2}$$SO$$_{4}$$$$cdot$$5H$$_{2}$$O and its effective spin model. Experimental studies by magnetic susceptibility, magnetization, heat capacity, and $$mu$$SR measurements indicate the absence of long-range order down to 0.4 K. Theoretical studies reveal that birchite is a model compound for the $${it J}$$$$_{1}$$-$${it J}$$$$_{2}$$ antiferromagnetic chain: the intrachain interactions $${it J}$$$$_{1}$$ and $${it J}$$$$_{2}$$ are antiferromagnetic and their magnitude is about 100 times larger than the interchain interactions. The magnitude of $${it J}$$$$_{2}$$ is two to three times larger than that of $${it J}$$$$_{1}$$, thus the spin gap is expected to be only a few percent of that of $${it J}$$$$_{1}$$. The temperature dependence of the specific heat shows a broad peak at about 1 K ($$simeq$$ 0.036 $${it J}$$$$_{1}$$), which suggests the presence of a spin gap.

Journal Articles

Breakdown of linear spin-wave theory and existence of spinon bound states in the frustrated kagome-lattice antiferromagnet

Mattan, K.*; Ono, Toshio*; Kawamura, Seiko; Nakajima, Kenji; Nambu, Yusuke*; Sato, Taku*

Physical Review B, 105(13), p.134403_1 - 134403_8, 2022/04

https://doi.org/10.1103/PhysRevB.105.134403
 Times Cited Count：3 Percentile：48.5(Materials Science, Multidisciplinary)

Spin dynamics of the spin-1/2 kagome-lattice antiferromagnet Cs$$_{2}$$Cu$$_{3}$$SnF$$_{12}$$ was studied using high-resolution, time-of-flight inelastic neutron scattering. The flat mode, a characteristic of the frustrated kagome antiferromagnet, and the low-energy dispersive mode, which is dominated by magnons, can be well described by the linear spin-wave theory. However, the theory fails to describe three weakly dispersive modes between 9 and 14 meV. These modes could be attributed to two-spinon bound states, which decay into free spinons away from the zone center and at a high temperature, giving rise to continuum scattering.

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

https://doi.org/10.1103/PhysRevB.105.L020408
 Times Cited Count：3 Percentile：48.5(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

Multiple magnetic bilayers and unconventional criticality without frustration in BaCuSi$$_2$$O$$_6$$

Allenspach, S.*; Biffin, A.*; Stuhr, U.*; Tucker, G. S.*; Kawamura, Seiko; Kofu, Maiko; Voneshen, D. J.*; Boehm, M.*; Normand, B.*; Laflorencie, N.*; et al.

Physical Review Letters, 124(17), p.177205_1 - 177205_7, 2020/05

https://doi.org/10.1103/PhysRevLett.124.177205
 Times Cited Count：10 Percentile：65.11(Physics, Multidisciplinary)

Journal Articles

Magnetic properties of one-dimensional quantum spin system Rb$$_2$$Cu$$_2$$Mo$$_3$$O$$_{12}$$ studied by muon spin relaxation

Kawamura, Seiko; Tomiyasu, Keisuke*; Koda, Akihiro*; Sari, D. P.*; Asih, R.*; Yoon, S.*; Watanabe, Isao*; Nakajima, Kenji

JPS Conference Proceedings (Internet), 21, p.011007_1 - 011007_5, 2018/03

https://doi.org/10.7566/JPSCP.21.011007

Rb$$_2$$Cu$$_2$$Mo$$_3$$O$$_{12}$$ is a one-dimensional quantum spin system with spin frustration. The magnetic ground state of this system has been expected to be incommensurate spin-singlet from a theoretical study. Furthermore, it was recently reported that this system exhibited ferroelectricity under a magnetic field. We carried out $$mu$$SR studies on this system to understand the magnetic properties. A slow muon spin relaxation due to nuclear dipoles is observed in the whole measured temperatures ranging from 0.06 K to 250 K, indicating that no magnetic ordering. The result suggests that the system shows a spin-singlet ground state. Furthermore, it was found that the distribution of the internal magnetic field were slightly enhanced below 10 K. This temperature dependence resembles that of the electric polarization observed in the magnetic field. It may indicate that some local anomaly of charge/spin related to the ferroelectricity is detected by a microscopic probe.

Journal Articles

Interaction of spin-orbital-lattice degrees of freedom; Vibronic state of the corner-sharing-tetrahedral frustrated spin system HoBaFe$$_{4}$$O$$_{7}$$ by dynamical Jahn-Teller effect

Kamazawa, Kazuya*; Ishikado, Motoyuki*; Kawamura, Seiko; Kawakita, Yukinobu; Kakurai, Kazuhisa*; Nakajima, Kenji; Sato, Masashi*

Physical Review B, 95(10), p.104413_1 - 104413_7, 2017/03

https://doi.org/10.1103/PhysRevB.95.104413
 Times Cited Count：2 Percentile：11.52(Materials Science, Multidisciplinary)

Journal Articles

Ground-state phase diagram of an anisotropic S=1/2 ladder with alternating rung interactions

Tonegawa, Takashi*; Okamoto, Kiyomi*; Hikihara, Toshiya*; Sakai, Toru

Journal of Physics; Conference Series, 683(1), p.012039_1 - 012039_7, 2016/02

https://doi.org/10.1088/1742-6596/683/1/012039
 Times Cited Count：2 Percentile：69.93(Materials Science, Multidisciplinary)

Employing mainly numerical methods, we explore the ground-state phase diagram of an anisotropic S=1/2 ladder, in which leg interactions are uniform and isotropic, while rung interactions are alternating and have a common Ising-type anisotropy. We determine the phase diagrams in some typical cases.

Journal Articles

Effect of monomer-monomer interactions on the phase diagrams of the S=1/2 distorted diamond type quantum spin chain

Okamoto, Kiyomi*; Tonegawa, Takashi*; Sakai, Toru

Journal of Physics; Conference Series, 683(1), p.012038_1 - 012038_6, 2016/02

https://doi.org/10.1088/1742-6596/683/1/012038
 Times Cited Count：2 Percentile：69.93(Materials Science, Multidisciplinary)

By use of mainly the exact diagonalization and the level spectroscopy method, we investigate the ground-state phase diagrams of the S=1/2 distorted diamond type quantum spin chain with the monomer-monomer interactions and ferromagnetic interactions. The magnetization plateau at 1/3 of the saturation magnetization was revealed to vanish in the region where the ferromagnetic interaction is rather strong.

Journal Articles

Magnetization process of the spin-S kagome-lattice Heisenberg antiferromagnet

Nakano, Hiroki*; Sakai, Toru

Journal of the Physical Society of Japan, 84(6), p.063705_1 - 063705_5, 2015/06

https://doi.org/10.7566/JPSJ.84.063705
 Times Cited Count：28 Percentile：80.64(Physics, Multidisciplinary)

The magnetization process of the spin-S Heisenberg antiferromagnet on the kagome lattice is studied by the numerical-diagonalization method. Our numerical-diagonalization data for small finite-size clusters with S=1, 3/2, 2 and 5/2 suggest that a magnetization plateau appears at one-third of the height of the saturation in the magnetization process irrespective of S. We discuss the S dependences of the edge fields and the width of the plateau in comparison with recent results by real-space perturbation theory.

Journal Articles

Neutron scattering investigation on quantum spin system SrCu$$_{2}$$(BO$$_{3}$$)$$_{2}$$

Kakurai, Kazuhisa; Nukui, Katsuyuki*; Aso, Naofumi*; Nishi, Masakazu*; Kadowaki, Hiroaki*; Kageyama, Hiroshi*; Ueda, Yutaka*; Regnault, L.-P.*; C$'e$pas, O.*

Progress of Theoretical Physics Supplement, (159), p.22 - 32, 2005/10

no abstracts in English

Journal Articles

High energy-resolution inelastic neutron scattering experiments on triplet bound state excitations in SrCu$$_{2}$$(BO$$_{3}$$)$$_{2}$$

Aso, Naofumi*; Kageyama, Hiroshi*; Nukui, Katsuyuki*; Nishi, Masakazu*; Kadowaki, Hiroaki*; Ueda, Yutaka*; Kakurai, Kazuhisa

Journal of the Physical Society of Japan, 74(8), p.2189 - 2192, 2005/08

https://doi.org/10.1143/JPSJ.74.2189
 Times Cited Count：8 Percentile：48.31(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Frustrating interactions and broadened magnetic excitations in the edge-sharing CuO$$_{2}$$ chains in La$$_{5}$$Ca$$_{9}$$Cu$$_{24}$$O$$_{41}$$

Matsuda, Masaaki; Kakurai, Kazuhisa; Lorenzo, J. E.*; Regnault, L. P.*; Hiess, A.*; Shirane, Gen*

Physical Review B, 68(6), p.060406_1 - 060406_4, 2003/08

https://doi.org/10.1103/PhysRevB.68.060406
 Times Cited Count：21 Percentile：68.23(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Polarized neutron scattering study of the CuO$$_{2}$$ chains in Ca$$_{2}$$Y$$_{2}$$Cu$$_{5}$$O$$_{10}$$

Matsuda, Masaaki; Nakamura, Mitsutaka; Takeda, Masayasu*; Kakurai, Kazuhisa; Yamaguchi, Hirotaka*; Ito, Toshimitsu*; Oka, Kunihiko*

Physica B; Condensed Matter, 329-333(1-4), p.711 - 712, 2003/05

https://doi.org/10.1016/S0921-4526(02)02020-3
 Times Cited Count：0 Percentile：0(Physics, Condensed Matter)

no abstracts in English

Journal Articles

Polarization dependence of spin excitations in BaCu$$_{2}$$Si$$_{2}$$O$$_{7}$$

Zheludev, A.*; Raymond, S.*; Regnault, L.-P.*; Essler, F. H. L.*; Kakurai, Kazuhisa; Masuda, Takatsugu*; Uchinokura, K.*

Physical Review B, 67(13), p.134406_1 - 134406_10, 2003/04

https://doi.org/10.1103/PhysRevB.67.134406
 Times Cited Count：21 Percentile：68.23(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Detailed magnetic structure of the coupled edge-sharing CuO$$_{2}$$ chains in Ca$$_{2+x}$$Y$$_{2-x}$$Cu$$_{5}$$O$$_{10}$$

Matsuda, Masaaki; Kakurai, Kazuhisa; Yamaguchi, Hirotaka*; Ito, Toshimitsu*; Lee, C.-H.*; Oka, Kunihiko*

Applied Physics A, 74(Suppl.1), p.S637 - S639, 2002/12

https://doi.org/10.1007/s003390201569
 Times Cited Count：3 Percentile：16.11(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Dominance of the excitation continuum in the longitudinal spectrum of weakly coupled heisenberg S=1/2 chains

Zheludev, A.*; Kakurai, Kazuhisa; Masuda, Takatsugu*; Uchinokura, K.*; Nakajima, Kenji*

Physical Review Letters, 89(19), p.197205_1 - 197205_4, 2002/11

https://doi.org/10.1103/PhysRevLett.89.197205
 Times Cited Count：23 Percentile：71.92(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Magnetic excitations in the quantum spin system NH$$_{4}$$CuCl$$_{3}$$

Osawa, Akira; Ono, Toshio*; Kakurai, Kazuhisa; Tanaka, Hidekazu*

Proceedings of Workshop on the Perspectives in Single Crystal Neutron Spectroscopy (SCNS 2002) (CD-ROM), 4 Pages, 2002/00

no abstracts in English

Journal Articles

Dzyaloshinski-Moriya interaction in the 2D spin gas system SrCu$$_{2}$$(BO$$_{3}$$)$$_{2}$$

C$'e$pas, O.*; Kakurai, Kazuhisa; Regnault, L. P.*; Ziman, T.*; Boucher, J. P.*; Aso, Naofumi*; Nishi, Masakazu*; Kageyama, Hiroshi*; Ueda, Yutaka*

Physical Review Letters, 87(16), p.167205_1 - 167205_4, 2001/10

https://doi.org/10.1103/PhysRevLett.87.167205
 Times Cited Count：103 Percentile：92.15(Physics, Multidisciplinary)

no abstracts in English

Oral presentation

Singlet-triplet transitions of ESR in gapped spin systems

Sakai, Toru; Hijii, Keigo*; Okubo, Susumu*; Ota, Hitoshi*

no journal, , 

The spin gap of the low-dimensional quantum spin systems and the strongly correlated electron systems is one of the interesting macroscopic quantum phenomena. Since the spin gap is the energy gap between the singlet ground state and the triplet excitation, the ESR direct transition is prohibited because of the spin conservation law. Thus the properties of the spin gap systems has been observed by some ESR transitions among the triplet excitations. Recently, however, the ESR direct transition corresponding to the spin gap was observed in several gapped spin systems. The mechanism of appearance of these prohibited ESR transition are supposed to be the Dzyaloshinsky-Moriya interaction and/or the staggered g-tensor. In order to identify the origin of the ESR direct transition, we gave some selection rules depending on the relative angle among the crystal axes of each material, the polarization of the microwave and the direction of external magnetic field.

27 (Records 1-20 displayed on this page)