Magnetic Neutron Scattering from Atoms Dissolved in Ferromagnetic Iron and Nickel

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Abstract
Recent experimental results giving the distribution of the magnetic-moment disturbance associated with solute atoms in ferromagnetic iron and nickel are summarized. The disturbances around transition elements dissolved in iron are of two quite different forms dependent on whether the element concerned lies to the right or to the left of iron in the periodic table. This suggests a dependence on the sign of an electrostatic perturbing potential and a discussion of this possibility is given in terms of a simple electron gas model. The two types of magnetic disturbance observed are not related by a sign reversal and the nonlinearity thus demanded by experiment is thought to result from limitations on electron-density increases imposed in iron by the restricted number of orbitals available at any one site. Experimental results for iron alloys containing nontransition-element solutes are also examined. Measurements on a wide range of both transition and nontransition elements dissolved in nickel are reviewed. Zn, Al, Ga, Si, Ge, Sn, Sb, V, Cr, Nb, Mo, Ru, W, and Re all result in a widespread loss of magnetic moment from the nickel host surrounding a solute site. The magnetic disturbances corresponding to these impurities differ in magnitude but show an approximately invariant shape. These defects are discussed in terms of bound impurity states and a molecular-field treatment involving a nonlocal and nonlinear susceptibility to represent the magnetic properties of nickel.