Solid State Communications Vol. 9, pp. 145—149, 1971. Pergamon Press. Printed in Great Britain EXCHANGE ENHANCEMENT OF THE SPIN SUSCEPTIBILITY OF METALS R. Dupree School of Physics, University of Warwick, Coventry, England and D.J.W. Geldart, Department of Physics, Dalhousie University, Halifax, Nova Scotia, Canada (Received 2 November 1970 by S. Lundqvist) We describe a new calculation from many body theory of the spin susceptibility of an interacting electron gas. The results are com- pared with the experimental data deduced for all the 18 non-transition liquid metals for which reliable measurements exist. Good agreement is obtained. DETERMINATION of the effects of electron— the density of electron states. This presents electron correlations on the properties of metals difficulty in the solid state since N(EF) can be has been an outstanding problem for many years. 1 strongly affected by the ionic potential and the Theoretically this has been due to the difficulty resulting band structure. In the case of liquid of carrying reliable calculations, for a complex metals however the ionic potential generally plays many body system, to the point of making direct a weaker role so that, with some exceptions, the comparison with experimental results. The extrac- electron states are closely free electron like. tion of a single effect is rarely possible since A determination of in the liquid state therefore most experimental phenomena are composite, in will generally yield a direct measure of ~. Since that they are affected not only by electron—electron the enhancement factor predicted by current theory interactions, but also, for example, by electron— depends only upon the conduction electron density phonon interactions, crystalline anisotropy, etc. it is of no importance in the calculation whether However, in the case of the conduction electron the metal is in the liquid or solid state. Unfor- spin susceptibility (X 3) in simple metals the tunately however, direct measurement (via con- electron correlations enter only as an enhancement duction electron spin resonance) of ~ has only of the Pauli susceptibility. The only other factor been made for liquid lithium and sodium and there which affects the spin susceptibility is the density are almost insurmountable experimental difficulties, of electron states, since the electron—phonon inter- due to the short electronic spin-lattice relaxation action plays a negligible role. For these reasons time, in extending these measurements to other the spin susceptibility is particularly well suited, liquid metals. in principle, to a detailed comparison of theory and experiment. In this paper we report such a In principle it is possible to obtain X~from a comparison which spans the physical range of measurement of the total susceptibility, ~ since conduction electron density occuring in metals. = — — Xd where X~ is the susceptibility of the ion cores and Xd the diamagnetic suscepti- In order to obtain the electronic enhancement bility of the conduction electrons. This is not factor, 77, from ~ it is first necessary to know usually considered to be a reliable method of 145