Anomalous Curie Response of Impurities in Quantum-Critical Spin-1/2 Heisenberg Antiferromagnets
Journal Article

Published: Friday, July 13, 2007
Citation: Physical Review Letters, Volume 99, Number 27205, Pages 4

Authors (2 total): K. H. Hoglund, A. W. Sandvik

Abstract: We consider a magnetic impurity in two different S=1/2 Heisenberg bilayer antiferromagnets at their respective critical interlayer couplings separating Néel and disordered ground states. We calculate the impurity susceptibility using a quantum Monte Carlo method. With intralayer 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 a symmetric bilayer are consistent with a universal C*.