Magnetic-Moment Distributions for3d-Transition-Metal Impurities in Cobalt

Abstract

Neutron diffuse scattering measurements were made on Co alloys containing 5 at.% V, Cr, Mn, and Ni impurities in order to determine the distribution of magnetic moment around the impurity sites. The measurements were made at room temperature on polycrystalline samples with 1.09-Å neutrons. The observed cross sections are of two types. The cross section of the Ni alloy is independent of the scattering vector and indicates that Ni impurities produce no moment disturbances on surrounding Co atoms. With V, Cr, or Mn impurities, the cross section decreases with increasing scattering vector in a manner which indicates that these impurities produce moment disturbances on their Co neighbors out to distances of approximately 5 Å. All three of these metals produce a net moment reduction when added to Co. For V and Cr, this is mostly due to the negative distrubances produced on the neighboring Co atoms. For Mn impurities, an oppositely aligned Mn moment makes an equally significant contribution to the observed moment reduction.