Staggered moment dependence on field-tuned quantum fluctuations in 2D frustrated antiferromagnets

Abstract

We propose an efficient method to identify the degree of frustration in quasi-2D antiferromagnets described by the J_1-J_2 Heisenberg model. The frustration ratio J_2/J_1 is usually obtained from analysis of susceptibility, specific heat and saturation field. We show that the non-monotonic field dependence of the staggered moment caused by the suppression of quantum fluctuations in a field depends strongly on the frustration ratio. This gives a powerful criterion to determine J_2/J_1 using a combination of exact diagonalization (ED) method for finite clusters and spin wave analysis. We apply this method to the quasi-2D compound Cu(pz)_2(ClO_4)_2 and show that it leads to an intermediate ratio J_2/J_1 ~ 0.2 for the frustration. We also explain the observed anomalous increase of transition temperature in applied fields as an effect of reduced quantum fluctuations.

5 pages, 5 figures, accepted for publication in Phys. Rev. B

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• Frustrated two dimensional quantum magnets
• Quasi-two-dimensional $S=1/2$ magnetism of Cu[C${}_6$H${}_2$(COO)${}_4$][C${}_2$H${}_5$NH${}_3$]${}_2$
• Square-lattice magnetism of diaboleite Pb2Cu(OH)4Cl2
• Quantum fluctuations in anisotropic triangular lattices with ferro- and antiferromagnetic exchange
• Switching of anisotropy and phase diagram of a Heisenberg square lattice S=1/2 antiferromagnet Cu(pz)2(ClO4)2
• Néel temperature and reentrant H-T phase diagram of quasi-2D frustrated magnets
• Magnetic Catalysis in Antiferromagnetic Films
• A case study of bilayered spin-$1/2$ square lattice compound [VO(HCOO)${}_2\cdot$(H${}_2$O)]
• Square-Lattice Antiferromagnet Subjected to a Magnetic Field Aligned with the Order Parameter