Field dependent neutron diffraction study in Ni50Mn38Sb12 Heusler alloy

In this paper, we present temperature and field dependent neutron diffraction (ND) study to unravel the structural and the magnetic properties in Ni50Mn38Sb12 Heusler system. This alloy shows martensitic transition from high temperature austenite cubic phase to low temperature martensite orthorhombic phase on cooling. At 3 K, the lattice parameters and magnetic moments are found to be almost insensitive to field. Just below the martensitic transition temperature, the martensite phase fraction is found to be 85%. Upon applying the field, the austenite phase becomes dominant, and the field induced reverse martensitic transition is clearly observed in the ND data. Therefore, the present study gives an estimate of the strength of the martensite phase or the sharpness of the martensitic transition. Variation of individual moments and the change in the phase fraction obtained from the analysis of the ND data vividly show the change in the magneto-structural state of the material across the transition

Where the atoms are Cation disorder and anion displacement in DIIXVI AIBIIIXVI2 semocinductors

Structural phase transitions tetragonal cubic dependent on composition as well as temperature were studied in ternary CuBIIIX2 chalcopyrites as well as 2 ZnX x CuInX2 1 x alloys B Ga, In; X S, Se, Te by neutron and synchrotron X ray powder diffraction. The transitions are due to a combination of disorder of the cation sublattice and displacement of the anion sublattice. The first goes along with a phase separation by chemical disorder, within a homologeous series depending on the size of the anion, for the same anion depending on the size of the cation B. The temperature dependent phase transition is clearly driven by a Cu B anti site occupancy. The order parameter of the phase transition, expressed as a difference in the number of electrons on the cation sites in the disordered and ordered phase, shows a critical behaviour with a critical exponent beta 0.35

Magnetic field dependent neutron powder diffraction studies of Ru0.9Sr2YCu2.1O7.9

Temperature and magnetic field dependent neutron diffraction has been used to study the magnetic order in Ru0.9Sr2YCu2.1O7.9. The appearance of (1/2, 1/2, 1/2), (1/2, 1/2, 3/2), and (1/2, 1/2, 5/2) peaks below TM = 140 K manifests the antiferromagnetic order. Neutron diffraction patterns measured in applied magnetic fields from 0 to 6 T show the destruction of the antiferromagnetic order with increasing field. There is no evidence of spontaneous or field-induced long range ferromagnetic order. This latter result contradicts the vast majority of other experimental observations for this system

Department NE Elastic Neutron Scattering. Annual report 1997-1999

SIGLEAvailable from TIB Hannover: ZA 4746(574) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Interplay between crystal and magnetic structures in YFe 2 (H α D 1−α ) 4.2 compounds studied by neutron diffraction

International audienc

Interplay between crystal and magnetic structures in YFe2 H alpha D1 alpha 4.2 compounds studied by neutron diffraction

We report a detailed magnetic structure investigation of YFe2 H alpha D1 alpha 4.2 alpha 0, 0.64, 1 compounds presenting a strong H,D isotope effect by neutron diffraction and Mossbauer spectroscopy analysis. They crystallize in the same monoclinic structure Pc space group with 8 inequivalent Fe sites having different H D environment. At low temperature, the compounds are ferromagnetic FM and show an easy magnetization axis perpendicular to the b axis and only slightly tilted away from the c axis. Upon heating, they display a first order transition from a ferromagnetic towards an antiferromagnetic AFM structure at T M0 which is sensitive to the H D isotope nature. The AFM cell is described by doubling the crystal cell along the monoclinic b axis. It presents an unusual coexistence of non magnetic Fe layer sandwiched by two thicker ferromagnetic Fe layers which are antiparallel to each other. This FM AFM transition is driven by the loss of ordered moment on one Fe site Fe7 through an itinerant electron metamagnetic IEM behaviour. The key role of the Fe7 position is assigned to both its hydrogen rich atomic environment and its geometric position. Above T M0 a field induced metamagnetic transition is observed from the AFM towards the FM structure accompanied by a cell volume increase. Both thermal and magnetic field dependence of the magnetic structure are found strongly related to the anisotropic cell distortion induced by H,D order in interstitial site