Effect of Spin-Orbit Interaction on the Spin Susceptibility of Small Particles

Abstract

Effect of spin-orbit interaction on the spin susceptibility of small metallic particles is investigated. Particles are so small that the spectrum of electronic excitations is discrete. It has been known that, in the absence of the spin-orbit interaction, a particle with an even number of conduction electrons has a vanishing susceptibility and a particle with an odd number of electrons shows a Curie-law susceptibility at temperatures lower than its finite energy level spacing. In the presence of spin-orbit interaction, the mixing of wave functions of the spin up and down states gives a significant contribution to the spin susceptibility. Conse-quently, a particle with an even or odd number of electrons has a nonvanishing or a modified Curie-type susceptibility, respectively, at low temperatures. Particularly, if the interaction is very strong, both are reduced to the Pauli paramagnetism.