Magnetic properties of layer compound CsVF4

Magnetic properties of CsVF₄ have been studied by means of thermal diffusivity and neutron diffraction. The antiferromagnetic transition appearing at about 43 K is found to be of Ising spin order of V³⁺ magnetic moments which are oriented along the c-axis having the order of G-type. By applying a magnetic field vertically to the c-plane, it is also found that the magnetic moments of V³⁺ are re-oriented so as to be anti-parallel in each two-dimensional sheet of VF₆ octahedra and parallel between the network with the result that a ferromagnetic component appears.     

Lattice dynamics of cupric oxide

By inelastic neutron scattering we have measured phonon dispersion curves of CuO in several directions. The phonon data are well reproduced by a 22 parameter rigid ion model. Various models with reduced numbers of fit parameters are described.     

Electrical conduction in manganese tungstate

The a.c. and d.c. electrical conductivity and thermoelectric power of a single crystal of MnWO₄ are reported in the temperature range 300–1200 K. It has been found that the dominant charge carriers are holes over the entire temperature range studied. A break in the log σ-($\text{1}\text{T}$) curve occurs around 600 K. The activation energies below and above this break temperature have been estimated as 0.53 and 0.57 eV. The charge carrier mobilities have also been estimated. The data have been analysed using the polaronic concept of electrical conduction.     

Mössbauer study of a single crystal of RbFeF4

Mössbauer measurements taken between 1.4 and 300 K on a single crystal of RbFeF₄ show that below the Néel temperature of 133.8 K the hyperfine field is at an angle of 16.5 ± 0.5° to the principal axis of the electric field gradient tensor. The hyperfine field is seen to be along the [001] axis allowing the identification of the principal axis of the EFG with the shortest ligand of the tilted FeF₆ octahedra that are constituents of the crystal structure. At 300 K the ratio of recoil-free fractions (?_⊥/?_:) is measured as 0.96 ± 0.05 but at 77 K the measured ratio is 1.7 ± 0.2.