TUE-CMS

Abstract: The electronic and magnetic properties of higher transition metal (TM) compounds often exhibit unusual properties due to the presence of strong spin-orbit coupling (SOC),which is comparable to their on-site Coulomb (U) and crystal field (ΔCFE)interactions. While quantum numbers ml (orbital) and ms (spin), for each electron can still be considered good and the spin-orbit coupled many body multiplets can be denoted by spectroscopic term symbols in the weak spin-orbit (L-S) coupling limit, the representation gets strongly modified for heavy multielectron elements having strong SOC. In such j-j coupling regime, total MJ (Σmj) becomes the only valid quantum number and the multiplets and their degeneracies are all solely determined? by the total angular momentum J. The electronic and magnetic response of a system in the j-j coupling limit are not yet well-understood and therefore, in the recent time, has generated significant curiosity. In this talk, I shall try to focus on different aspects of this unusual electronic state and the consequent magnetic states with a special emphasis on hexagonal ruthenates and iridates..