Energy splittings of transition metal ions in non-cubic hosts

A number of recent experiments have shown evidence for energy splittings of paramagnetic ions in metallic hosts. Although theoretical attempts have been made to calculate so called ’’crystal field effects’’ in metals from first principles very little qualitative progress has been made on this very difficult subject. In this paper we wish to present a short summary of experimental results on the energy splittings of the manganese ion in h.c.p. hosts: Mg, Zn and Cd and also the energy splittings of two species of transition metal ions Mn and Cr in the same host-metal, zinc. This summary of results will be compared with the recent theoretical work of Smith who considers spin-orbit effects in metals. At least semi-qualitative agreement is found in that the observed energy splittings scale with the spin-orbit parameter of the host and the magnitude of the local moment-conduction electron exchange interaction strength.