Quantum dimer phases in a frustrated spin ladder: Effective field theory approach and exact diagonalization

Field-induced quantum soliton lattice in a frustrated two-leg spin-1/2 ladder.

Based on high-field (31)P nuclear magnetic resonance experiments and accompanying numerical calculations, it is argued that in the frustrated S=1/2 ladder compound BiCu(2)PO(6) a field-induced soliton lattice develops above a critical field of μ(0)H(c1)=20.96(7) T. Solitons result from the fractionalization of the S=1, bosonlike triplet excitations, which in other quantum antiferromagnets are c...

Spin dynamics in a double quantum dot: Exact diagonalization study

Quantum Phases in Two-dimensional Frustrated Spin-1/2 Antiferromagnets

Investigating various spin-1/2 systems in two dimensions (2d), by means of exact diagonalization (ED) on small samples of N spins, we have found, up to now, four kinds of antiferromagnetic phases at T=0. Two of them display long range order (LRO): Néel or Valence Bond Crystal (VBC) LRO. The others are two different Spin-Liquids. The Néel case may be qualified as semi-classical: it is a groundst...

Large-S approach to chiral phases in frustrated spin chains

A large-S approach to the description of chiral phases in frustrated antiferromagnetic spin-S chains with easy-plane anisotropy is proposed. The approach is valid in the vicinity of the classical Lifshitz point j = 1 4 , where j is the relative strength of the frustrating next-nearest-neighbor coupling. The effective theory turns out to be the nonlinear σ-model with the additional fourth-order ...

Non - linear Field Theory of a Frustrated Heisenberg Spin Chain

We derive a continuum field theory for the Majumdar-Ghosh model in the large-S limit, where the field takes values in the manifold of the SO(3) group. No topological term is induced in the action and the cases for integer spin and half-integer spin appear to be indistinguishable. A one-loop β−function calculation indicates that the theory flows towards a strong coupling (disordered) phase at lo...