Pressure dependence of the hyperfine field in Eu intermetallics

Recent measurements of the pressure dependence of the hyperfine field at the Eu nucleus in Eu intermetallic compounds have been interpreted by terms of volume dependence of the transferred field and variations of the local-moment—conduction-electron exchange parameters. It is suggested that an alternative solution may be the pressure dependence of number $d$ electrons at the rare-earth site and its influence upon the self-polarization field. A test of the validity of the latter hypothesis is suggested.