Wednesday, July 4, 2012

1207.0095 (Cédric Weber et al.)

Anticollinear magnetic order induced by impurities in the frustrated
Heisenberg model of pnictides
   [PDF]

Cédric Weber, Frédéric Mila
We present Monte Carlo simulations for a classical antiferromagnetic Heisenberg model with both nearest ($J_1$) and next-nearest ($J_2$) exchange couplings on the square lattice in the presence of non-magnetic impurities. We show that the order-by-disorder entropy selection, associated with the Ising-like phase transition that appears for $J_2/J_1>1/2$ in the pure spin model, is quenched at low temperature due to the presence of non-magnetic impurities. Evidences that a new competing order is stabilized around the impurities, and in turn induces a re-entrance phase transition are reported. Implications for local magnetic measurement of the parent compound of iron pnictides are briefly discussed.
View original: http://arxiv.org/abs/1207.0095

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