We consider the instability of the ground state of the Δ chain against a lattice distortion increasing the bond strength (λ) in each triangle. It relaxes the frustration and causes a remarkable gap enhancement; only a 6% increase of λ doubles the gap compared to the fully-frustrated case (λ = 1). The lowest excitation is revealed to be a kink-antikink bound state whose correlation length decreases drastically with λ increase. The enhancement follows a power law, ΔEgap ∼ (λ - 1) + 1.44(λ - 1)2/3, which can be obtained from the exact result of the continuum model.
|ジャーナル||Physics Letters, Section A: General, Atomic and Solid State Physics|
|出版ステータス||Published - 1997 2月 3|
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