Two-dimensional magnetism in α-CuV2 O6

Abstract

Several previous studies reported that a one-dimensional Heisenberg chain model is inadequate in describing the magnetic properties of the low-dimensional quantum antiferromagnet α-CuV2O6, but the origin for this observation has remained unclear. We have reinvestigated the magnetic properties of α-CuV2O6 and found that our anisotropic magnetic susceptibility, neutron-powder diffraction, and electron paramagnetic spin-resonance measurements are in good agreement with extensive density-functional theory (DFT+U) total energy calculations which indicate that the correct spin lattice model for α-CuV2O6 is rather a S=1/2 2D-Heisenberg antiferromagnetic lattice. The magnetic susceptibility data are well described by a rectangular Heisenberg antiferromagnet with anisotropy ratio α∼ 0.7 consistent with the DFT results. Quantum Monte Carlo simulations of the magnetic susceptibilities for a rectangular lattice Heisenberg antiferromagnet were performed in the anisotropy range 0.5 ≤α≤ 1.0. The results of the Quantum Monte Carlo calculations were cast into a Padé approximant which was used to fit the temperature-dependent magnetic susceptibility data. Neutron-powder-diffraction measurements were used to conclusively solve the collinear antiferromagnetic structure of α-CuV2O6 below the Néel temperature of ∼22.4 K.