Abstract
The 151Eu Mossbauer resonance has been used to study magnetic exchange interactions involving diamagnetic Eu3+ ions in antiferromagnetic SrEu2Fe2O7. The odd number of neighbouring magnetic ions results in a large induced magnetic flux density at the europium nucleus, and a small quadrupole effect. The experimental data are combined with a detailed calculation of the exchange and crystal-field interactions to resolve an ambiguity in the magnetic lattice as determined from neutron diffraction data, and it is concluded that the Fe3+ spins are normal to the (110) mirror planes.