Speaker
Description
The increasing interest of using ferroic and multiferroic materials in high-tech applications requires that the underlying physical phenomena are studied on an atomic scale. Time-differential perturbed correlation (TDPAC) measurements have a local character and can provide important information concerning combined magnetic dipole and electric quadrupole interactions in ferroic and multiferroic systems. With the application of characterization techniques and radioactive beams, this method has become very powerful, especially for the determination of the temperature dependence of the hyperfine parameters even at elevated-temperatures. Such measurements lead to a better understanding of phase transitions, including observations of local environments in low fractions of different phases. Several facilities are used at ISOLDE-CERN benefiting from the multitude of available beams adequate to the use and development of the TDPAC technique. Moreover, the concentration of required TDPAC probes is so small that the probes negligibly affect the observed transition temperatures. The polarization of the TDPAC probe nucleus during the measurements of ferroics systems is due to the transferred spin density. This phenomenon gives rise to the so called “super transference” of the magnetic hyperfine field in perovskites. An overview of prior literature intercalated with a discussion of measurement conditions and isotopes is presented. Particular emphasis is given to the important case of measurements carried out at ISOLDE-CERN employing the 111mCd as a probe.
