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85

Sep 22, 2013
09/13

by
S. Miyahara; N. Furukawa

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We propose a new mechanism to induce a novel one-magnon excitation by the electric component of light in cycloidal spin states, i.e. so called electromagnon process. We calculated optical spectra in the cycloidal spin structures as observed in multiferroic perovskite manganites RMnO3 where novel magnetic excitations induced by oscillating electric fields are observed. When symmetric spin-dependent electric polarizations are introduced, we have light absorptions at terahertz frequencies with...

Source: http://arxiv.org/abs/0811.4082v1

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11

Jun 29, 2018
06/18

by
Y. Suzuki; H. Nakada; S. Miyahara

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The M3Y-type semi-realistic interaction is applied to deformed nuclei for the first time. The constrained Hartree-Fock calculations assuming axial symmetry are implemented for the $N=20$ isotones $^{30}$Ne, $^{32}$Mg, $^{34}$Si and the $N=28$ isotones $^{40}$Mg, $^{42}$Si, $^{44}$S with the M3Y-P6 interaction. The results match the experimental data well. Effects of the realistic tensor force on the nuclear quadrupole deformation are investigated in relation to the loss of the $N=20$ and $28$...

Topic: Nuclear Theory

Source: http://arxiv.org/abs/1604.03202

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49

Sep 18, 2013
09/13

by
K. Matsuda; S. Miyahara; N. Furukawa

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In this paper, we carry out a new technique named projection ED and indicate that it is applicable to the frustrated models, e.g., XXZ spin-1/2 Heisenberg and spinless fermion t-V models, in the strong coupling limit with highly degenerate ground states in a general way. As an example, we deal with a spinless fermion t-V model on a triangular lattice and show the usefulness of the method.

Source: http://arxiv.org/abs/0806.2197v1

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70

Sep 18, 2013
09/13

by
K. Totsuka; S. Miyahara; K. Ueda

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By using perturbation calculation and numerical diagonalization, low-energy spin dynamics of the Shastry-Sutherland model is investigated paying particular attention to the two-particle coherent motion. In addition to spin-singlet- and triplet bound states, we find novel branches of coherent motion of a bound quintet pair, which are usually unstable because of repulsion. Unusual dispersion observed in neutron-scattering measurements are explained by the present theory. The importance of the...

Source: http://arxiv.org/abs/cond-mat/0101125v1

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111

Jul 22, 2013
07/13

by
M. Miyazaki; C. Hotta; S. Miyahara; K. Matsuda; N. Furukawa

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We analyze a model of spinless fermions on a triangular lattice at half-filling interacting via strong nearest-neighbor repulsive interactions, V, using the variational Monte Carlo simulation technique. The existence of three-sublattice long-range order is confirmed by the finite-size scaling analysis of the charge structural factor at V_c/t > 12. This ordered phase shows characteristics expected for a so called "pinball liquid" state, which has the spontaneous separation of...

Source: http://arxiv.org/abs/0807.3615v1

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93

Jul 19, 2013
07/13

by
H. Murakawa; Y. Onose; S. Miyahara; N. Furukawa; Y. Tokura

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We have investigated the variation of induced ferroelectric polarization under magnetic field with various directions and magnitudes in a staggered antiferromagnet Ba$_2$CoGe$_2$O$_7$. While the ferroelectric polarization cannot be explained by the well-accepted spin current model nor exchange striction mechanism, we have shown that it is induced by the spin-dependent $p$-$d$ hybridization between the transition-metal (Co) and ligand (O) via the spin-orbit interaction. On the basis of the...

Source: http://arxiv.org/abs/1005.4986v1

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53

Sep 23, 2013
09/13

by
S. Kuroiwa; A. Nakashima; S. Miyahara; N. Furukawa; J. Akimitsu

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The full-potential linear augmented plane-wave calculations have been applied to investigate the systematic change of electronic structures in CaAlSi due to different stacking sequences of AlSi layers. The present ab-initio calculations have revealed that the multistacking, buckling and 60 degrees rotation of AlSi layer affect the electronic band structure in this system. In particular, such a structural perturbation gives rise to the disconnected and cylindrical Fermi surface along the M-L...

Source: http://arxiv.org/abs/0710.3437v1

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46

Sep 23, 2013
09/13

by
S. Miyahara; K. Takubo; T. Suzuki; T. Katsufuji; N. Furukawa

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Unconventional peak structure in the Raman spectra due to magnon excitation at low temperature is observed in spinel magnet ${\rm MnV_2O_4}$, where a noncollinear spin state is realized by geometrical frustration. We propose a new mechanism to induce such a Raman scattering process due to a one-magnon excitation of the noncollinear spin state. Novel features of the scattering such as selection rules and peak position observed experimentally in ${\rm MnV_2O_4}$ can be explained quite naturally...

Source: http://arxiv.org/abs/1012.4073v1

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43

Sep 20, 2013
09/13

by
K. Kodama; S. Miyahara; M. Takigawa; M. Horvatic; C. Berthier; F. Mila; H. Kageyama; Y. Ueda

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We observed a field-induced staggered magnetization in the 2D frustrated dimer-singlet spin system SrCu2(BO3)2 by 11B NMR, from which the magnitudes of the intradimer Dzyaloshinsky-Moriya interaction and the staggered g-tensor were determined. These anisotropic interactions cause singlet-triplet mixing and eliminate a quantum phase transition at the expected critical field Hc for gap closing. They also provide a quantitative account for some puzzling phenomena such as the onset of a uniform...

Source: http://arxiv.org/abs/cond-mat/0404482v3

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47

Sep 20, 2013
09/13

by
Y. Takahashi; S. Ishiwata; S. Miyahara; Y. Kaneko; N. Furukawa; Y. Taguchi; R. Shimano; Y. Tokura

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We have investigated electrically-active magnetic excitations (electromagnons) in perovskite manganites with the $E$-type (up-up-down-down) spin structure by terahertz spectroscopy. Eu$_{1-x}$Y$_x$MnO$_3$ (0.1$\le x\le$1) and Y$_{1-y}$Lu$_y$MnO$_3$ (0$\le y\le$1) without magnetic $f$-moments, which host collinear sinusoidal, $A$-type, cycloidal, and $E$-type spin orders, are used to examine the systematics of possible electromagnons. Three-peak structures (23, 35, 45 cm$^{-1}$) of magnetic...

Source: http://arxiv.org/abs/1002.3676v1

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42

Sep 19, 2013
09/13

by
S. Miyahara; J. -B. Fouet; S. R. Manmana; R. M. Noack; H. Mayaffre; I. Sheikin; C. Berthier; F. Mila

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We investigate the interplay of Dzyaloshinskii-Moriya interactions and an external field in spin 1/2 dimers. For isolated dimers and at low field, we derive simple expressions for the staggered and uniform magnetizations which show that the orientation of the uniform magnetization can deviate significantly from that of the external field. In fact, in the limit where the ${\bf D}$ vector of the Dzyaloshinskii-Moriya interaction is parallel to the external field, the uniform magnetization...

Source: http://arxiv.org/abs/cond-mat/0610861v1

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78

Jul 20, 2013
07/13

by
M. Clemancey; H. Mayaffre; C. Berthier; M. Horvatic; J. -B. Fouet; S. Miyahara; F. Mila; B. Chiari; O. Piovesana

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We present a $^2$D NMR investigation of the gapped spin-1/2 compound $Cu_2 (C_5 H_{12} N_2)_2 Cl_4$. Our measurements reveal the presence of a magnetic field induced transverse staggered magnetization (TSM) which persists well below and above the field-induced 3D long-range magnetically ordered (FIMO) phase. The symmetry of this TSM is different from that of the TSM induced by the order parameter of the FIMO phase. Its origin, field dependence and symmetry can be explained by an intra-dimer...

Source: http://arxiv.org/abs/cond-mat/0609496v1

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45

Sep 18, 2013
09/13

by
H. Ichikawa; L. Kano; M. Saitoh; S. Miyahara; N. Furukawa; J. Akimitsu; T. Yokoo; T. Matsumura; M. Takeda; K. Hirota

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We have observed the orbital ordering in the ferromagnetic Mott-insulator Lu2V2O7 by the polarized neutron diffraction technique. The orbital ordering pattern determined from the observed magnetic form factors can be explained in terms of a linear combination of wave functions |yz>, |zx> and |xy>; |0> = (1/3)^(1/2) |xy> + (1/3)^(1/2)|yz> + (1/3)^(1/2) |zx> which is proportional to |(x + y + z)^2 - r^2>; where each orbital is extended toward the center-of-mass of the V...

Source: http://arxiv.org/abs/cond-mat/0502020v1

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62

Sep 23, 2013
09/13

by
N. Kida; Y. Takahashi; J. S. Lee; R. Shimano; Y. Yamasaki; Y. Kaneko; S. Miyahara; N. Furukawa; T. Arima; Y. Tokura

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Recent spectroscopic studies at terahertz frequencies for a variety of multiferroics endowed with both ferroelectric and magnetic orders have revealed the possible emergence of a new collective excitation, frequently referred to as electromagnon. It is magnetic origin, but becomes active in response to the electric field component of light. Here we give an overview on our recent advance in the terahertz time-domain spectroscopy of electromagnons or electric-dipole active magnetic resonances,...

Source: http://arxiv.org/abs/0904.4796v1

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51

Sep 22, 2013
09/13

by
D. C. Johnston; M. Troyer; S. Miyahara; D. Lidsky; K. Ueda; M. Azuma; Z. Hiroi; M. Takano; M. Isobe; Y. Ueda; M. A. Korotin; V. I. Anisimov; A. V. Mahajan; L. L. Miller

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A comprehensive theoretical and experimental study is presented of the magnetic susceptibility versus temperature \chi(T) of spin S = 1/2 two- and three-leg Heisenberg ladders and ladder oxide compounds. Extensive quantum Monte Carlo simulations of \chi(T) were carried out for both isolated and coupled two-leg ladders with spatially anisotropic intraladder exchange. Accurate fits to these and related literature QMC data were obtained. We have also calculated the one- and two-magnon dispersion...

Source: http://arxiv.org/abs/cond-mat/0001147v1