G. L. Bychkov

Crystal growth of solid solutions based on the YAl3(BO3)4, NdAl3(BO3)4 and GdAl3(BO3)4 borates

Abstract Single crystals of NdxY1−xAl3(BO3)4 (NYAB) and GdxY1−xAl3(BO3)4 (GYAB) have been grown from fluxed melts based on the potassium trimolybdate by both the TSSG method and spontaneous crystallization. Neodymium and gadolinium are practically uniformly distributed over the entire volume of crystals. The effective segregation coefficients of neodymium and gadolinium were found to be 0.3–0.8 and about 1 for NYAB and GYAB, respectively. In the case of NYAB, this coefficient increases with an increase in crystallization temperature and a decrease in the crystal growth rate. Growth striations are developed on the trigonal prism faces of the NYAB and GYAB crystals enriched by NAB and GAB which tend to form the monoclinic structures.

Magnetic phase transitions in TbBaCo2O5.5 single crystals

Magnetization studies have been carried out on a single crystal of TbBaCo2O5.5 in the temperature range 2–350 K and magnetic fields up to 50 kOe. Several spontaneous magnetic phase transitions have been observed and analysed in both Co (TC = 277 K, TN1 = 210 K) and Tb (TN2 = 3.44 K) subsystems. It is shown that the spontaneous first-order phase transition at TN1 from an antiferromagnetic to a weak ferromagnetic state is accompanied by an intermediate state. The properties of this state are strongly determined by the thermo-magnetic history of the sample. Metamagnetic type transitions have been observed at 140 K< T<190 K for the Co subsystem and at T<TN2 for the Tb subsystem. The analysis of the magnetic properties of TbBaCo2O5.5 points to the strongly anisotropic character of the Tb and Co subsystems. The Tb subsystem was shown to be of the Ising type. For this subsystem, the exchange interactions between nearest neighbours and next-nearest neighbours were determined. The observed properties of the Co subsystem also point to the Ising character of the Co ions. The effect of the twinning structure on magnetization processes of the weak ferromagnetic phase, especially hysteresis curves, is discussed.

X-ray diffraction study of superstructure in GdBaCo{sub 2}O{sub 5.5}

A single crystal of

Magnetization and magnetotransport of LBaCo2O5.5(L=Gd, Eu) single crystals

\mathrm{Gd}\mathrm{Ba}{\mathrm{Co}}_{2}{\mathrm{O}}_{5.47(2)}

Magnetic anisotropy in detwinned Tb0.9Dy0.1BaCo2O5.5 single crystal

has been studied by means of x-ray diffraction. Below the first-order metal-insulator transition, a continuous transition to a phase with a doubled orthorhombic unit cell is discovered at

Flux growth, composition, structural and thermal characteristics of (RxY1−x)Al3(BO3)4 (R=Nd, Gd; x=1, 0.6, 0.65, 0.7 and 0.75) crystals

{T}_{C}=341.5(7)

Seeded growth from flux and neutron study of La1-xBaxMnO3 (0.2 < x < 0.5) single crystals

by the appearance of very weak superstructure reflections. The critical exponent for the order parameter is found to be

Magnetotransport properties of flux melt grown single crystals of Co-substituted manganites with perovskite structure

\ensuremath{\beta}=0.328(8)

Evolution of the commensurate and incommensurate magnetic phases of the S?=?3/2 kagome staircase Co3V2O8?in an applied field

, indicating an Ising pseudospin ordering in a 3D system. The systematic extinction of the superstructure reflections evidences the crystal symmetry change from

X-ray and neutron diffraction studies of coupled structural phase transitions in DyBaCo2O5.5

Pmmm