Unveiling spin-orbit coupling e ects on the electronic states of multi-orbital Transition Metal Oxides

Transition Metal Oxides (TMOs) show a wealth of intriguing properties which are governed by the interplay of charge, spin, and orbital degrees of freedom. Moreover, the comprehension of the features of strongly correlated TMOs with signi cant Spin Orbit Coupling (SOC) represents a challenging work and the interplay between large SOC and lattice geometry is undoubt- edly a relevant ingredient in the exploration of such features. The most dramatic example of that occurs in iridates, where SOC deeply impacts the magnetic state, changing the character of the multiplet state within the t 2g manifold in the case of an octahedral arrangement of the ions. Corresponding e ects in eg manifold have rarely been considered, due to the conventional wisdom that eg subshells ensure a perfectly quenched orbital momentum. In the rst part of the thesis, we study the in uence of SOC on the magnetic state of a d1 TM ion located in a tetrahedral environment, proving that its e ect can be strongly enhanced in the case of distorted geometry. Under this condition, our theoretical research reveals that SOC can induce a substantial anisotropic unquenched orbital angular momentum and can a ect the hier- archy of the lowest energy levels involved in the magnetic superexchange. … [edited by Author]