N ov 1 99 4 RANDOM FRUSTRATION IN TWO - DIMENSIONAL SPIN - 1 / 2 HEISENBERG ANTIFERROMAGNET
نویسنده
چکیده
The square lattice spin-1/2 antiferromagnet containing a dilute concentration, δ, of randomly placed ferromagnetic nearest-neighbor bonds is studied at low-temperature via nonlinear σ-model techniques and by exact diagonalization. We generally find that long-range Néel order is destroyed above a critical strength in the defective ferromagnetic exchange coupling-constant given by |Kc|/J ∼ δ . We also observe large statistical fluctuations both in the spin-stiffness and in the antiferromagnetic structure-factor near this critical point, suggesting the onset of a spin-glass phase. PACS Indices: 75.10.Jm, 75.50.Ee, 75.50.Lk, 74.20.Mn
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تاریخ انتشار 1994