Collapse of the Small‐Angle Magnon Scattering in Fe as a Function of Magnetic Field

The dependence of the spin wave energy on the magnetization M⇒ and the applied magnetic field H⇒ in Fe (and other ferromagnets) has not been very well investigated with neutrons. According to the Holstein‐Primakoff dispersion relation, the contributions of the Zeeman energy gμBHgμBH and the dipole‐dipole interactions 4π gμBM sin2θq4πgμBMsin2θq do not simply add linearly to the exchange energy Dq2. However, in order to see these contributions, one must observe the very low energy (.01 – .1 mev) spin waves. One of the predictions of this dispersion relation is that the scattering of neutrons by spin waves near the origin should disappear as the magnetic field is increased. This is a consequence of the kinematics of the scattering process. Using our double‐Si crystal technique for small angle scattering we have experimentally observed this collapse at a field of about 8 kG in Fe at room temperature as predicted by theory. We have also measured the scattering due to these very low energy spin waves at temperatures up to .7 Tc and compared the data on an absolute scale with the theoretical cross section. The agreement is reasonably good.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87920/2/1340_1.pd

Direct Observation of the Angular Distribution of Neutrons Scattered at Small Angles by Spin Waves in Fe☒Ni Alloys

Extensive measurements of the small‐angle scattering of neutrons by spin waves in Fe☒Ni alloys using polycrystalline samples and a polyenergetic beam have been made by Hatherly et al. Their spin‐wave stiffness D was found not to agree with later measurements using the diffraction method on Fe0.5Ni0.5 and Fe0.2Ni0.8 single crystals. In an effort to resolve this disagreement we employed a new technique to observe the small‐angle scattering by spin waves in these materials that uses a double‐Si‐crystal spectrometer, monoenergetic neutrons, and single‐crystal samples. Our result for D for the Fe0.5Ni0.5 sample agrees with the previous single‐crystal data. However our data on Fe0.2Ni0.8 is in closer agreement with the earlier small‐angle scattering measurements. The effect of the dipole‐dipole interaction on the spin‐wave energy has been clearly observed in Fe0.5Ni0.5. Two discontinuities are predicted and observed to occur in the scattering profiles. However, an additional discontinuity is observed in our Fe0.7Ni0.3 single crystal, which may indicate another scattering surface of unknown origin.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70819/2/JAPIAU-41-3-1363-1.pd

Divorced yet still together: ongoing personal relationship and coparenting among divorced parents

Due to copyright restrictions, the access to the full text of this article is only available via subscription.This study examined the ongoing personal and emotional involvement between former spouses and its association with perceptions of the quality of the coparenting relationship. Dyadic analysis of 54 formerly married couples revealed that both men and women rate their coparenting relationship as better when they also report ongoing personal and emotional involvement with their former spouse. Furthermore, when men reported ongoing involvement, their former wives reported better coparenting. The opposite effect was not found. This pattern held for both Black Americans and White Americans. Clinical implications of the findings of this study are also discussed.National Institute of Child Health and Human Developmen

Single-Step Production of Nanostructured Copper-Nickel (CuNi) and Copper-Nickel-Indium (CuNiIn) Alloy Particles

Nanostructured copper-nickel (CuNi) and copper-nickel-indium (CuNiIn) alloy particles were produced from aqueous solutions of copper, nickel nitrates and indium sulfate by hydrogen reduction-assisted ultrasonic spray pyrolysis. The effects of reduction temperatures, at 973 K, 1073 K, and 1173 K (700 A degrees C, 800 A degrees C, and 900 A degrees C), on the morphology and crystalline structure of the alloy particles were investigated under the conditions of 0.1 M total precursor concentration and 0.5 L/min H-2 volumetric flow rate. X-ray diffraction studies were performed to investigate the crystalline structure. Particle size and morphology were investigated by scanning electron microscope and energy-dispersive spectroscopy was applied to determine the chemical composition of the particles. Spherical nanocrystalline binary CuNi alloy particles were prepared in the particle size range from 74 to 455 nm, while ternary CuNiIn alloy particles were obtained in the particle size range from 80 to 570 nm at different precursor solution concentrations and reduction temperatures. Theoretical and experimental chemical compositions of all the particles are nearly the same. Results reveal that the precursor solution and reduction temperature strongly influence the particle size of the produced alloy particles