Hall coefficient signals orbital differentiation in the Hund's metal Sr$_2$RuO$_4$

Manuel Zingl (1) , Jernej Mravlje (2) , Markus Aichhorn (3) , Olivier Parcollet (4, 1) , Antoine Georges (1, 5, 6, 7)

1 Flatiron Institute
2 IJS - Jozef Stefan Institute [Ljubljana]
3 TU Graz - Graz University of Technology [Graz]
4 IPHT - Institut de Physique Théorique - UMR CNRS 3681
5 CPHT - Centre de Physique Théorique [Palaiseau]
6 DQMP - Department of Quantum Matter Physics [Geneva]
7 Collège de France - Chaire Physique de la matière condensée (A. Georges)

The Hall coefficient R$_H$ of Sr$_2$RuO$_4$ exhibits a non-monotonic temperature dependence with two sign reversals. We show that this puzzling behavior is the signature of two crossovers, which are key to the physics of this material. The increase of R H and the first sign change upon cooling are associated with a crossover into a regime of coherent quasiparticles with strong orbital differentiation of the inelastic scattering rates. The eventual decrease and the second sign change at lower temperature are driven by the crossover from inelastic to impurity-dominated scattering. This qualitative picture is supported by quantitative calculations of R$_H$(T) using the Boltzmann transport theory in combination with dynamical mean-field theory, taking into account the effect of spin–orbit coupling. Our insights shed new light on the temperature dependence of the Hall coefficient in materials with strong orbital differentiation, as observed in Hund’s metals.

Domaines: Physique [physics]

Manuel Zingl, Jernej Mravlje, Markus Aichhorn, Olivier Parcollet, Antoine Georges. Hall coefficient signals orbital differentiation in the Hund's metal Sr$_2$RuO$_4$. Npj Quantum Materials, 2019, 4, pp.35. ⟨10.1038/s41535-019-0175-y⟩. ⟨cea-04541157⟩