Magnetic properties of the Ce2Fe17 xMnx helical magnets up to high magnetic fields

Magnetic properties of the Ce2Fe17 xMnx, x 0 2, alloys in magnetic fields up to 40 T are reported. The compounds with x 0.5 1 are helical antiferromagnets and those with 1oxp2 are helical ferromagnets or helical antiferromagnets at low and high T, respectively. Mn ions in the system carry average magnetic moment of 3.070.2 mB that couple antiparallelly to the Fe moments. Easy plane magnetic anisotropy in the Ce2Fe17 xMnx compounds weakens upon substitution of Mn for Fe. The absolute value of the first anisotropy constant in the Ce2Fe17 xMnx helical ferromagnets decreases slower with increasing temperature than that calculated from the third power of the spontaneous magnetization. Noticeable magnetic hysteresis in the Ce2Fe17 xMnx, x 0.5 2, helical magnets over the whole range of magnetic fields reflects mainly irreversible deformation of the helical magnetic structure during the magnetization of the compounds. A contribution from short range order SRO magnetic clusters to the magnetic hysteresis of the helical magnets has been also estimate

Angular dependence of saturation magnetization in single crystals with uniaxial magnetic anisotropy

A remarkable feature of some high anisotropy intermetallic compounds based on R-T systems, where R stands for a rare earth atom and T is a 3d transition metal element, is a prominent difference of saturation magnetization along easy and hard magnetization axes: MEA and MHA. This anisotropy of saturation magnetization needs to be considered when magnetization curves are evaluated to derive the magnetic anisotropy constants

Pre-organization of diarylideneacetonyl crownophanes in single crystals to photochemical transformations

Specific features of crystal packings and pre-organization of diarylideneacetonyl crownophane molecules to solid-phase photochemical transformations were studied on the basis of X-ray diffraction data using methods of simulation of molecular crystal packings. The tendency of the most part of the synthesized macrocyclic E,E-isomers to the formation of homochiral crystals (P212121) was revealed, while (23E,26E)-11,12,14,15-tetrahydro-8H-dinaphtho-[2,1-k:1′,2′-r][1,4,7, 10]tetraoxacyclononadecine-23,26-dien-25(9H)-one is prone to polymorphism. A phenomenon of solid-phase stereospecific photochemical dimerization of molecules according to the syn-head-to-tail type without crystal destruction (single crystal-single crystal transformation) was found for one of the modifications of this crownophane. © 2011 Springer-Verlag