3 papers
cond-mat.str-el1999
Quantum Phase Transitions in Two-Dimensional Spin Systems with Ladder, Plaquette and Mixed-Spin Structures
A. Koga, S. Kumada, N. Kawakami
Quantum phase transitions between the magnetically ordered and disordered states are studied for the two-dimensional antiferromagnetic quantum spin systems with ladder, plaquette,…
cond-mat.str-el1998
Two-Dimensional Quantum Spin Systems with Ladder and Plaquette Structure
A. Koga, S. Kumada, N. Kawakami
We investigate low-energy properties of two-dimensional quantum spin systems with the ladder and plaquette structures, which are described by a generalized antiferromagnetic Heisen…
cond-mat.str-el1997
Mixed-Spin Ladders and Plaquette Spin Chains
A. Koga, S. Kumada, N. Kawakami +1
We investigate low-energy properties of a generalized spin ladder model with both of the spin alternation and the bond alternation, which allows us to systematically study not only…