A method to calculate the dynamical as well as the static properties of the Ising ferromagnet, developed in the previous paper for the two-dimensional square lattice, is extended to cubic lattices. The temperature dependence of the frequency-dependent magnetic susceptibility, approach to equilibrium of the magnetization of the system, the fluctuation-dissipation theorem, and some static properties are calculated. It is proved that all these properties are essentially the same for cubic lattices and for two-dimensional model. It is further demonstrated by explicit calculation that the non-linear effect is very important for the critical slowing-down near the Curie point, especially in the ferromagnetic region.A method to calculate the dynamical as well as the static properties of the Ising ferromagnet, developed in the previous paper for the two-dimensional square lattice, is extended to cubic lattices. The temperature dependence of the frequency-dependent magnetic susceptibility, approach to equilibrium of the magnetization of the system, the fluctuation-dissipation theorem, and some static properties are calculated. It is proved that all these properties are essentially the same for cubic lattices and for two-dimensional model. It is further demonstrated by explicit calculation that the non-linear effect is very important for the critical slowing-down near the Curie point, especially in the ferromagnetic region.

Journal of the Physical Society of JapanAug 1, 196715 citations

Operators and Dynamical Variables

Pedro Pereyra Padilla

Undergraduate lecture notes in physicsJan 1, 20121 citation

Dynamical properties of the honeycomb-lattice iridates Na2IrO3

Takafumi Suzuki, Takuto Yamada, Youhei Yamaji +1 more

We investigate the dynamical properties of ${\mathrm{Na}}_{2}{\mathrm{IrO}}_{3}$ . For five effective models proposed for ${\mathrm{Na}}_{2}{\mathrm{IrO}}_{3}$ , we numerically calculate dynamical structure factors (DSFs) with an exact diagonalization method. An effective model obtained from ab initio calculations explains inelastic neutron scattering experiments adequately. We further calculate excitation modes based on linearized spin-wave theory. The spin-wave excitation of the effective models obtained by ab initio calculations disagrees with the low-lying excitation of DSFs. We attribute this discrepancy to the location of ${\mathrm{Na}}_{2}{\mathrm{IrO}}_{3}$ in a parameter space close to the phase boundary with the Kitaev spin-liquid phase.We investigate the dynamical properties of ${\mathrm{Na}}_{2}{\mathrm{IrO}}_{3}$. For five effective models proposed for ${\mathrm{Na}}_{2}{\mathrm{IrO}}_{3}$, we numerically calculate dynamical structure factors (DSFs) with an exact diagonalization method. An effective model obtained from ab initio calculations explains inelastic neutron scattering experiments adequately. We further calculate excitation modes based on linearized spin-wave theory. The spin-wave excitation of the effective models obtained by ab initio calculations disagrees with the low-lying excitation of DSFs. We attribute this discrepancy to the location of ${\mathrm{Na}}_{2}{\mathrm{IrO}}_{3}$ in a parameter space close to the phase boundary with the Kitaev spin-liquid phase.

arXiv:1507.06044Physical Review BNov 16, 201519 citations

States and Dynamical Variables

Umberto Lombardo, G. Giuliani, Yifei Niu

UNITEXT for physicsJan 1, 20240 citations

We investigate the dynamical properties of

{\mathrm{Na}}_{2}{\mathrm{IrO}}_{3}

. For five effective models proposed for

{\mathrm{Na}}_{2}{\mathrm{IrO}}_{3}

, we numerically calculate dynamical structure factors (DSFs) with an exact diagonalization method. An effective model obtained from ab initio calculations explains inelastic neutron scattering experiments adequately. We further calculate excitation modes based on linearized spin-wave theory. The spin-wave excitation of the effective models obtained by ab initio calculations disagrees with the low-lying excitation of DSFs. We attribute this discrepancy to the location of

{\mathrm{Na}}_{2}{\mathrm{IrO}}_{3}

in a parameter space close to the phase boundary with the Kitaev spin-liquid phase.