Nuclear interactions in europium vanadate

The ground configuration of the europium ion, Eu 3+ , 4f 6 , 7 F, is split by spin-orbit interaction into a series of levels J = 0 to 6. There are matrix elements of the electronic Zeeman interaction Z e and hyperfine interaction Z hfs between states of different J . In particular, for the lowest state, the singlet J = 0, matrix elements to the first excited state J = 1 produce contributions to the nuclear Zeeman and electric quadrupole interactions in J = 0. Formulae for these are listed by Bleaney & Leask (1994) for three tetragonal compounds. One of these is EuVO 4 , for which existing measurements by optical ‘hole-burning’ are discussed, together with the possibility of nuclear orientation and dynamic nuclear polarization. Experiments using nuclear acoustic resonance are suggested in a following paper.