Perturbed angular correlation (PAC) spectroscopy as a tool for the study of ferroelectrics

Perturbed angular correlation (PAC) of nuclear radiation has proven to be a useful tool for the characterization of materials. The technique makes use of the hyperfine interaction between the nuclear electromagnetic moments and the electromagnetic environment in which the nucleus finds itself. It is sensitive to the strength, electric or magnetic character, microscopic symmetry, and time dependence of these fields, as well as the overall symmetry and texture of the sample. Of particular interest for the study of ferroelectric materials is the electric-quadrupole hyperfine interaction, which is capable of distinguishing the point symmetry around the probe atom with great precision. In principle, PAC is also sensitive to fluctuations of the hyperfine fields in the neighborhood of phase transition temperatures, leading to the possibility of using this technique to study defect dynamics and critical phenomena as well.

Keywords:

• perturbed angular correlation
• electric-quadrupole interaction
• phase transitions
• critical phenomena