Mössbauer measurement of the hyperfine magnetic field AT sp site in Heusler alloys Rh2 Mn Z (Z=In and Sb)

We have investigated the systematics of hyperfine magnetic field on a fixed probe at the Z-site in Heusler alloys Rh₂MnZ as the valence of Z (sp element) is varied. The hmf on¹¹⁹Sn in Rh₂MnIn_.98 ¹¹⁹Sn₀₂ has been measured at 293K and 77K. In Rh₂Mn_1.12Sb_.86 ¹¹⁹Sn_.02 the hmf on¹²¹Sb has been measured at 77 K, and on¹¹⁹Sn at 293 K and 77 K. The results are compared with the hmf on¹¹⁹Sn in Rh₂Mn Ge_.98 ¹¹⁹Sn_.02 Rh₂Mn Sn, and Rh₂Mn Pb_.98 ¹¹⁹Sn_.02.Supported by the University Research Council, University of CincinnatiSupported by the Natural Sciences and Engineering Research Council of Canada     

A Mössbauer effect and X-ray diffraction study of Fe–Ga–Al thin films prepared by combinatorial sputtering

A combinatorial thin film library of the composition Fe_100−yGa_y−xAl_x was prepared by magnetron sputtering. The composition was determined by electron microprobe and showed that the Fe content was reasonably constant across the library and the Al to Ga ratio varied linearly with position. The crystallographic structure was determined with X-ray diffraction and found to be bcc. ⁵⁷Fe Mössbauer spectroscopy was used to investigate short-range order within the film. It was shown that non-magnetic atoms tend to cluster in these alloys, but that the substitution of Al for Ga reduced this tendency. This behavior may be, at least partially, responsible for the decrease in saturation magnetostriction between Fe–Ga and Fe–Al alloys.     

Synthesis and characterization of silica nanosprings by a low temperature chemical vapor deposition

Silica nanosprings were synthesized using a simple, low temperature, chemical vapor deposition method via a vapor–liquid–solid mechanism. Nanosprings with excellent uniformity and helicity in high and repeatable yields have been observed. The morphology and crystal structure of the nanosprings were characterized by scanning electron microscopy and transmission electron microscopy. The chemical composition of the nanosprings was determined using the energy-filtered transmission electron microscopic method. The as-grown nanomaterials were confirmed to be amorphous silica with irregularly shaped Au catalytic particles located at the tips. In addition, we propose a spontaneous spinning growth model to explain the formation of such helical nanostructures.     

Three-dimensional magneto-optic trap for micro-object manipulation

A magneto-optic trap for micro-objects is described. Magnetic beads were trapped by optical tweezers while being rotated by a new integrated magnetic manipulator. Rotation was achieved with eight electromagnets with tip-pole geometry. The time orbital potential technique was used to achieve rotation of magnetic beads. Trapping in three dimensions and rotation of magnetic beads on three axes are demonstrated with forces up to 230 pN and force momenta of up to 10(-16)N m . A position-detection apparatus based on an interferometric scheme provides nanometer sensitivities in a few milliseconds.     

Sn hyperfine field trends in the Heusler alloys Co2Mn(Al,Si)

Hyperfine Interactions - The Sn hyperfine field in the series of Heusler alloys Co2MnAl0.98−xSixSn0.02 (x=0.00, 0.20, 0.40, 0.58, 0.78, 0.98) has been measured at 77 K using119Sn...     

Effects of rapid quenching on the structural and magnetic properties of the Heusler alloy Cu2MnSn

The Heusler alloy Cu₂MnSn has been prepared by two methods; (1) the conventional method of annealing for an extended period of time just below the melting temperature, followed by quenching into ice water, and (2) rapid quenching from the melt onto the surface of a rotating Cu disc. X-ray diffraction and ¹¹⁹Sn Mössbauer effect measurements show that the annealed sample contains a significant quantity of a non-magnetic impurity phase while the rapidly quenched sample is essentially free from non-Heusler phases.