1,364 research outputs found
Modulation structure of a frustrated spin ladder
We study a two-leg spin-1/2 ladder with isotropic exchanges and biquadratic
interactions in the basic plaquettes. It is shown that for the extremely
frustrated case, the system exhibits a self-organized phase separation. In some
parameter regions, the singlet rungs form a Wigner-like lattice in the
triplet-rung host. There are three types of elementary excitations in this
modulation phase, i.e., the spinons in a triplet domain, the broken singlet
rungs and the deformation of the Wigner-like lattice. The flux phase induced by
an external magnetic field in the rung-dimerized phase is also discussed.Comment: 7 pages Revtex, no figure, to appear in Int. J. Mod. Phys. 2
Phase diagram of frustrated mixed-spin ladders in the strong-coupling limit
We study the ground-state properties of frustrated Heisenberg ferrimagnetic
ladders with antiferromagnetic exchange interactions and two types of
alternating sublattice spins. In the limit of strong rung couplings, we show
that the mixed spin-1/2 and spin-1 ladders can be systematically mapped onto a
spin-1/2 Heisenberg model with additional next-nearest-neighbor exchanges. The
system is either in a ferrimagnetic state or in a critical spin-liquid state
depending on the competition between the spin exchanges along the legs and the
diagonal exchanges.Comment: 6 pages, 2 figur
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