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Frustrated Heisenberg antiferromagnet on a pyrochlore lattice
Akihisa Koga, Norio Kawakami
We investigate quantum phase transitions for the antiferromagnetic Heisenberg model on a pyrochlore lattice. By means of a series expansion starting from isolated tetrahedr…
Ground-State Phase Diagram for the Three-Dimensional Orthogonal-Dimer System
Akihisa Koga
We investigate quantum phase transitions in the three-dimensional orthogonal-dimer system of the compound by means of the series expansion technique. We then d…
First-order quantum phase transition in the orthogonal-dimer spin chain
Akihisa Koga, Kouichi Okunishi, Norio Kawakami
We investigate the low-energy properties of the orthogonal-dimer spin chain characterized by a frustrated dimer-plaquette structure. When the competing antiferromagnetic couplings…
Quantum Phase Transitions in the Shastry-Sutherland Model for
Akihisa Koga, Norio Kawakami
We investigate the quantum phase transitions in the frustrated antiferromagnetic Heisenberg model for by using the series expansion method. It is found that a…
Magnetic Double Structure for S=1, 1/2 Mixed-Spin Systems
Y. Takushima, A. Koga, N. Kawakami
We investigate the zero-temperature and the finite-temperature properties of the two-dimensional antiferromagnetic quantum spin system composed of the s=1/2 and s=1 spins. The spin…