Nuclear techniques like perturbed angular correlation (PAC) and perturbed angular distribution (PAD), involving hyperfine interaction between a nuclear probe and the electromagnetic fields produced by atomic electronic states in a solid, provde a elegant and accurate tool to study various aspects of condensed matter physics viz. electronic and magnetic properties at short length and time scales. With the help of energetic heavy ion beams from an accelerator like the Pelletron facility, it is not only possible to produce a wide variety of probes but also implant them into hosts (recoil implantation) that are other wise inaccessible by conventional methods. Over the past years we have carried out several experiments to study some problems like formation and stability of magnetic moment on d/f ions embedded in different metallic hosts. Some of our important findings are
i) Observation of giant 4d magnetic moment on Rh atom in Pd and Pt metal.
ii) Elucidation of moment stabilizing influence of ferromagnetic host spin polarization. Compared to conventional Kondo type antiferromagnetic spin polarization that always increase spin fluctuation and hence destabilize the magnetic moment, we have shown that ferromagnetic polarization of host conduction electrons lead to suppressed spin fluctuation rates and hence a more stable magnetic moment.
More recently via in beam TDPAD measurement we have found evidence for the existence of highly stable 4d magnetic moment on interstitial Mo atoms in Yb host. It should be noted that at interstitial lattice sites due to enormously large overlap of atomic orbitals, Mo atoms are not expected to develop local magnetic moment. Another important mile stone of our studies is the successful demonstration of Kondo behaviour of Fe impurities in Ag nanoparticles. Compared to Fe in bulk Ag, in the nanoparticles we find a ten fold increase in the magnitude of Kondo temperature Tk . Employing PAC technique we have also studied static and dynamic spin correlation in some Uranium based heavy fermion systems. The results provide clear indication that the manifestations of “heavy fermions” viz. enhancement of electronic specific heat can arise from dynamic spin correlation between U atoms without any enhancement of electronic mass.