Electronic correlations and screening effects in the Hund's polar metal SrEuMo$_2$O$_6$

Abstract

Using a first-principles approach based on density functional theory and dynamical mean field theory, we study the electronic properties of a new candidate polar metal SrEuMo$_2$O$_6$. Its electronic structure shares similarities with centrosymmetric SrMoO$_3$ and EuMoO$_3$, from which it may be considered an ordered derivative, but ferroelectric-like distortions of the divalent cations and oxygen anions lift inversion symmetry mediated by an anharmonic lattice interaction in the metallic state. We find that Hund's coupling promotes the effects of electronic correlations owing to the Mo$^{4+}$ $d^{2}$ electronic configuration, producing a correlated metallic phase far from the Mott state. The contraindication between metallicity and polar distortions is thereby alleviated through the renormalized quasiparticles, which are unable to fully screen the ordered local dipoles.