Intrinsic effects of the boundary condition on the switching process of spin crossover solids (2009)
Nishino, Masamichi, Enachescu, Cristian, Miyashita, Seiji, Boukheddaden, Kamel, Varret, Francois
We investigated clustering dynamics of domains in switching processes between the low spin (LS) and high spin (HS) phases in thermal induced hysteresis loops of spin-crossover (SC) solids. In SC...
Nagaoka ferromagnetism in large-spin systems -Fermion and Boson systems-- (2009)
Miyashita, Seiji, Ogata, Masao, De Raedt, Hans
We study magnetic properties of itinerant quantum magnetic particles described by a generalized Hubbard model with large spin ($S>1/2$) which may be realized in optical lattices of laser-cooled atom...
Saeki, Mizuhiko, Uchiyama, Chikako, Mori, Takashi, Miyashita, Seiji
Relation among various expressions of the complex admittance for quantum systems in contact with heat reservoir is studied. Exact expressions of the complex admittance are derived in various types of...
Quantum Annealing for Clustering (2009)
Kurihara, Kenichi, Tanaka, Shu, Miyashita, Seiji
This paper studies quantum annealing (QA) for clustering, which can be seen as an extension of simulated annealing (SA). We derive a QA algorithm for clustering and propose an annealing schedule,...
Quantum Annealing for Variational Bayes Inference (2009)
Sato, Issei, Kurihara, Kenichi, Tanaka, Shu, Nakagawa, Hiroshi, Miyashita, Seiji
This paper presents studies on a deterministic annealing algorithm based on quantum annealing for variational Bayes (QAVB) inference, which can be seen as an extension of the simulated annealing for...
Hijii, Keigo, Miyashita, Seiji
We study structure of the gapless points (diabolical points) at zero magnetic field ($H_z=0$) of single-spin models with spin anisotropies. Nontrivial appearance of diabolical points at finite...
Master equation approach to line shape in dissipative systems (2009)
Uchiyama, Chikako, Aihara, Masaki, Saeki, Mizuhiko, Miyashita, Seiji
We propose a formulation to obtain the line shape of a magnetic response with dissipative effects that directly reflects the nature of the environment. Making use of the fact that the time evolution...
Miyashita, Seiji, Rikvold, Per Arne, Mori, Takashi, Konishi, Yusuké, Nishino, Masamichi, Tokoro, Hiroko
Photo-induced switching from the low-spin state to the high-spin state is studied in a model of spin-crossover materials, in which long-range interactions are induced by elastic distortions due to...
Scaling properties of the relaxation time near the mean-field spinodal (2009)
Mori, Takashi, Miyashita, Seiji, Rikvold, Per Arne
We study the relaxation processes of the infinitely long-range interaction model (the Husimi-Temperley model) near the spinodal point. We propose a unified finite-size scaling function near the...
Quantum Spinodal Phenomena (2009)
Miyashita, Seiji, De Raedt, Hans, Barbara, Bernard
We study the dynamical magnetization process in the ordered ground-state phase of the transverse Ising model under sweeps of magnetic field with constant velocities. In the case of very slow sweeps...
Mechanism of Slow Relaxation due to Screening Effect in a Frustrated System (2007)
We study a slow relaxation process in a frustrated spin system in which a kind of screening effect due to frustrated environment plays an important role. This screening is attributed to highly...
Wave Packet Propagation and Electric Conductivity of Nanowires (2003)
Maeda, Munehiko, Saito, Keiji, Miyashita, Seiji, De Raedt, Hans
We compute the electric conductivity of nanowires in the presence of magnetic domain walls by the method of wave packet propagation. We demonstrate that the propagation through the wire depends on...
Characterization of the Energy Structure and Adiabatic Magnetization Process of V15 (2002)
Rudra, Indranil, Saito, K., Ramasesha, S., Miyashita, Seiji
The energy structure of the V$_{15}$ is studied using exact diagonalization methods, and the adiabatic changes of the magnetization in the system with the sweeping field are investigated. We confirm...
Nishino, Masamichi, Saito, Keiji, Miyashita, Seiji
We study effect of noise on the tunneling process of the magnetization in a sweeping field from the viewpoint of the nonadiabatic transition. The tunneling probability depends on the properties of...
Takasu, Masako, Miyashita, Seiji, Suzuki, Masuo, Kanada, Yasumasa
The S = 1/2 ferromagnetic XY model on the triangular lattice is investigated by quantum Monte Carlo methods based on the Suzuki-Trotter formula. The squared magnetization (M2x) / N2 is calculated for...
Ordering process of the antiferromagnetic Heisenberg model on the square is investigated mainly by a quantum Monte Carlo method. The effect of quantum fluctuation is studied by investigating the...