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Nakano, Hiroki*; Sakai, Toru
Journal of Physics; Conference Series, 868, p.012006_1 - 012006_10, 2017/07
Times Cited Count：3 Percentile：78.7(Physics, Applied)The spin gap issue of the kagome lattice antiferromagnet is investigated by the finite size scaling analysis applied for the energy spectrum of the rhombic clusters calculated by the numerical exact diagonalization. The conclusion is that the kagome lattice antiferromagnet is gapless, as well as the triangular lattice one.
Sakai, Toru; Nakano, Hiroki*
Physics Procedia, 75, p.369 - 375, 2015/12
Times Cited Count：1 Percentile：46.45(Physics, Applied)The S=1/2 three-leg quantum spin tube is investigated using the numerical diagonalization. The study indicated a new quantum phase transition between the 1/3 magnetization plateau phase and the plateauless one, with respect to the spin anisotropy. The phase diagram is also presented.
Sakai, Toru; Kasahara, Toshihiro*; Hijii, Keigo*; Ota, Hitoshi*; Nakano, Hiroki*
Synthetic Metals, 208, p.26 - 28, 2015/10
Times Cited Count：1 Percentile：4.82(Materials Science, Multidisciplinary)The S=1/2 three-leg spin nanotube with the ring exchange interaction at each plaquette is investigated using the numerical diagonalization of finite-size systems. The previous work suggested that the system without the ring exchange interaction has a spin excitation gap between the singlet ground state and the triplet excitation, because a spontaneous dimerization occurs in the ground state. The present study indicates that as the ring exchange increases, a quantum phase transition occurs at some critical value to another spin gap phase where the pattern of the dimerization is different from the initial one.
Sakai, Toru; Hijii, Keigo*; Okubo, Susumu*; Ota, Hitoshi*; Nakano, Hiroki*; Miyashita, Seiji*
Applied Magnetic Resonance, 46(9), p.997 - 1002, 2015/09
Times Cited Count：1 Percentile：6.49(Physics, Atomic, Molecular & Chemical)The S=1/2 kagome-lattice antiferromagnet is investigated by the numerical diagonalization of 18-spin finite-size cluster. The matrix elements proportional to the intensity of the singlet-triplet ESR transition are calculated in the presence of the Dzyaloshinsky-Moriya interaction. Some angle-dependent selection rules is also proposed.
Kolezhuk, A. K.*; Glazkov, V. N.*; Tanaka, Hidekazu*; Osawa, Akira
Physical Review B, 70(2), p.020403_1 - 020403_4, 2004/07
Times Cited Count：44 Percentile：83.59(Materials Science, Multidisciplinary)Recently measured high-field ESR spectra of the spin dimer material TlCuCl
are described within the framework of an effective field theory. A good agreement between the theory and experiment is achieved, for all geometries and in a wide field range, under the assumption of a weak anisotropy of the interdimer as well as intradimer exchange interaction.
Osawa, Akira; Kakurai, Kazuhisa; Osakabe, Toyotaka; Nakamura, Mitsutaka; Takeda, Masayasu; Tanaka, Hidekazu*
Journal of the Physical Society of Japan, 73(6), p.1446 - 1449, 2004/06
Times Cited Count：33 Percentile：77.73(Physics, Multidisciplinary)no abstracts in English
Vyaselev, O.*; Takigawa, Masashi*; Vasiliev, A.*; Osawa, Akira; Tanaka, Hidekazu*
Physical Review Letters, 92(20), p.207202_1 - 207202_4, 2004/05
Times Cited Count：37 Percentile：79.57(Physics, Multidisciplinary)We report the results of Cu and Cl nuclear magnetic resonance experiments and thermal expansion measurements in magnetic fields in the coupled dimer spin system TlCuCl. We found that the field-induced antiferromagnetic transition as confirmed by the splitting of NMR lines is slightly discontinuous. The abrupt change of the electric field gradient at the Cl sites, as well as the sizable change of the lattice constants, across the phase boundary indicate that the magnetic order is accompanied by simultaneous lattice deformation. These results suggest the importance of the spin-lattice correlations in this system.
Osawa, Akira; Fujisawa, Masashi*; Osakabe, Toyotaka; Kakurai, Kazuhisa; Tanaka, Hidekazu*
Journal of the Physical Society of Japan, 72(5), p.1026 - 1029, 2003/05
Times Cited Count：60 Percentile：87.55(Physics, Multidisciplinary)no abstracts in English
Mg
)ClOsawa, Akira; Fujisawa, Masashi*; Kakurai, Kazuhisa; Tanaka, Hidekazu*
Physical Review B, 67(18), p.184424_1 - 184424_8, 2003/05
Times Cited Count：31 Percentile：77.52(Materials Science, Multidisciplinary)no abstracts in English
Yasuoka, Hiroshi
Journal of the Physical Society of Japan, 69(suppl.B), p.161 - 172, 2000/00
no abstracts in English
Ca
)Cu
O
; Neutron inelastic scattering studyKatano, Susumu; *; Akimitsu, Jun*; Nishi, Masakazu*; Kakurai, Kazuhisa*
Physical Review Letters, 82(3), p.636 - 639, 1999/01
Times Cited Count：65 Percentile：88.72(Physics, Multidisciplinary)no abstracts in English
CaCuO*; *; *; Akimitsu, Jun*; Katano, Susumu; Nishi, Masakazu*; Kakurai, Kazuhisa*
Journal of Physics and Chemistry of Solids, 60(8-9), p.1039 - 1043, 1999/00
Times Cited Count：3 Percentile：23.12(Chemistry, Multidisciplinary)no abstracts in English
CaCuOKatano, Susumu; *; *; Akimitsu, Jun*; Nishi, Masakazu*; Kakurai, Kazuhisa*
Physica B; Condensed Matter, 259-261, p.1046 - 1047, 1999/00
Times Cited Count：10 Percentile：51.95(Physics, Condensed Matter)no abstracts in English
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.
Sakai, Toru; Kasahara, Toshihiro*; Nakano, Hiroki*; Hijii, Keigo*; Okunishi, Koichi*; Okamoto, Kiyomi*
no journal, ,
We report the result from the theoretical study based on the numerical diagonalization and the finite-size scaling analysis, on the quantum phase transition which occurs when the ratio of the rung coupling, the leg coupling and the ring exchange interactions is varied, in the S=1/2 three-leg spin tube.
