Investigation of some metallic trilayer nickelates analogous to high Tc cuprates

Abstract

The triple layer T'-structure compounds (Rn+1NinO2n+2 for n=3) have the mixed valent state of Ni1+/Ni2+ which is analogous to the electronic configuration of Cu2+/Cu3+ in the high temperature superconducting cuprates (HTSC). Hence such nickelates provide a fitting experimental platform to study their similarities as well as their differences with the HTSCs. In this work, we tried to obtain the R4Ni3O8 (R = La, Pr and Nd) compounds by subjecting the parent Ruddlesden Popper series members i.e. R4Ni3O10 (R = La, Pr and Nd) to reducing conditions. The reducing conditions had to be precisely determined using the TGA setup. The R4Ni3O10 members were synthesized by optimizing the sol-gel technique in which the citrate route was adopted. Structural, magnetic and electrical transport properties of R4Ni3O10 samples were characterized. These low temperature physical property measurements revealed some new anomalies which were not reported earlier in the literature. In this thesis, we have attempted to gain insight into the origin of these anomalies.