Chemical and Magnetic Order in the Heusler Alloy Ni2Mn0.8V0.2Sn By Neutron Diffraction

Abstract

<p> Neutron diffraction techniques have been used to determine the chemical and magnetic order in a single crystal of the Heusler alloy Ni2Mn0.8v0.2sn. This material orders in the Heusler L21 structure and is ferromagnetic. Nuclear Bragg scattering intensity ratios have been measured at 298 K and compared with nuclear structure factor calculations based on a model of the crystal structure. This comparison is used to determine chemical disorder. Magnetic Bragg scattering intensity ratios have been measured at 117 K. These ratios, along with bulk magnetization measurements, are used to determine the spatial distribution of the magnetic moment. The crystal is found to have the L21 structure with possibly 5% or so Ni-Sn disorder. Nearly all of the magnetic moment, which is 3.19 ± .03 μ8/mol, is found to exist on the Mn-V sites. The rest is present on the Sn atoms. The values 3.74 ± .10 μ8/Mn atom and .21 ± .08 μ8/Sn atom result from assuming the V atoms carry no moment. </p>