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Anomalous Curie response of impurities in quantum-critical spin-1/2 Heisenberg antiferromagnets

K. H. Hoglund·A. W. Sandvik
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Abstract

We consider a magnetic impurity in two different S=1/2 Heisenberg bilayer antiferromagnets at their respective critical inter-layer couplings separating N'eel and disordered ground states. We calculate the impurity susceptibility using a quantum Monte Carlo method. With intra-layer couplings in only one of the layers (Kondo lattice), we observe an anomalous Curie constant C*, as predicted on the basis of field-theoretical work [S. Sachdev et al., Science 286, 2479 (1999)]. The value C*=0.262 +/- 0.002 is larger than the normal Curie constant C=S(S+1)/3. Our low-temperature results for the symmetric bilayer are consistent with a universal C*.

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K. H. Hoglund, A. W. Sandvik. 2007-07-29. Anomalous Curie response of impurities in quantum-critical spin-1/2 Heisenberg antiferromagnets. https://arxiv.org/abs/cond-mat/0701472

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