Critical neutron scattering in a uniaxial relaxor Sr$_{0.6}$Ba$_{0.4}$Nb$_2$O$_6$

This paper reports on the results of an investigation into the temperature evolution of the critical scattering of neutrons in the strontium barium niobate crystal SBN60 in a zero field and in applied external direct-current (dc) electric fields. It has been shown that the observed critical scattering consists of two components that are adequately described by a Lorentzian and a Lorentzian squared. These components differently depend on the temperature and the momentum transfer vector. The application of an external electric field significantly suppresses the second component.