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Sakai, Toru; Kasahara, Toshihiro*; Hijii, Keigo*; Ota, Hitoshi*; Nakano, Hiroki*
Synthetic Metals, 208, p.26 - 28, 2015/10
Times Cited Count：1 Percentile：4.78(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.
Kambe, Shinsaku; Sakai, Hironori; Tokunaga, Yo; Lapertot, G.*; Matsuda, Tatsuma*; Knebel, G.*; Flouquet, J.*; Walstedt, R. E.*
Nature Physics, 10(11), p.840 - 844, 2014/11
Times Cited Count：18 Percentile：70.89(Physics, Multidisciplinary)In new observations reported here, we find that coexisting, static Fermi liquid and non-Fermi liquid states are a key feature of the QCPT in YbRh
Si. By means of nuclear magnetic resonance (NMR) spin-lattice relaxation time measurements on a single crystal sample, it is revealed that the FL and NFL states are invariant,while their relative proportion in a crossover is field dependent near the QCPT. Such a pair of states has remained hidden in Ce compounds, owing presumably to short lifetimes for the two states. A new scaling law for the occupation ratio of the two states is derived, and could be widely applicable to Kondo-lattice systems
Sakai, Toru; Sato, Masahiro*; Okunishi, Koichi*; Okamoto, Kiyomi*; Itoi, Chigaku*; Nakano, Hiroki*
no journal, ,
The S=1/2 spin nanotube is theoretically investigated by the numerical diagonalization and the density matrix renormalization group. We found some new quantum phase transitions with respect to the ratio of the leg and rung exchange interactions. Some interesting quantum phenomena in the carrier doped spin tube will be also discussed.
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.
