Spin-orbit coupling and k-dependent Zeeman splitting in strontium ruthenate

Area of Science:

• Condensed Matter Physics
• Materials Science

Background:

• Investigating the electronic properties of strontium ruthenate (Sr2RuO4) is crucial for understanding its exotic magnetic and superconducting behaviors.
• Spin-orbit coupling significantly influences the electronic band structure and Fermi surface topology in strongly correlated materials like Sr2RuO4.

Purpose of the Study:

• To compare relativistic local density approximation (LDA) calculations of the Sr2RuO4 Fermi surface with experimental spin-orbit coupling data.
• To investigate the k-dependence of Zeeman splitting on the alpha Fermi surface sheet and its implications for theoretical models.

Main Methods:

• Relativistic local density approximation (LDA) band structure calculations.
• Modeling quasi-particle bands using tight-binding models.
• Analysis of de Haas-van Alphen (dHvA) experimental data to probe spin-orbit coupling effects.

Main Results:

• A strong k-dependent Zeeman splitting on the alpha Fermi surface sheet is observed experimentally.
• Bare LDA bands alone do not fully explain the observed k-dependent Zeeman splitting.
• Tight-binding models consistent with dHvA experiments require a restricted parameter set.

Conclusions:

• The findings suggest that additional charge transfer, potentially indicated by dynamical mean-field theory (DMFT) calculations, is necessary to reconcile LDA predictions with experimental results.
• The study reinforces that the spin-orbit coupling in Sr2RuO4 is substantial, challenging theories that propose rotation of the triplet d-vector at low magnetic fields.