First-Principles Correlated Approach to the Normal State of Strontium Ruthenate

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Strontium ruthenate (Sr₂RuO₄) exhibits unconventional superconductivity, with its pairing symmetry influenced by multiple electronic bands, correlations, and spin-orbit coupling.
• Understanding the normal state, particularly the temperature-dependent incoherence-coherence crossover, is crucial for elucidating the superconducting mechanism.

Purpose of the Study:

• To revisit the normal state properties of Sr₂RuO₄ using advanced theoretical methods.
• To provide a unified and quantitative description of the material's unusual physical responses in the normal state.
• To identify the microscopic origins of unconventional superconductivity in Sr₂RuO₄.

Main Methods:

• First-principles calculations incorporating electronic correlations.
• Analysis of the temperature-dependent incoherence-coherence crossover.
• Modeling of multi-orbital charge fluctuations within a Hund's metal framework.

Main Results:

• A unified and quantitative description of various unusual normal state physical responses in Sr₂RuO₄ was achieved.
• The study highlights the significance of multi-orbital charge fluctuations as a potential pairing glue.
• A direct connection between normal state behavior and the emergence of superconductivity was established.

Conclusions:

• Dominant multi-orbital charge fluctuations in a Hund's metal are proposed as a key factor for unconventional superconductivity in Sr₂RuO₄.
• This work provides a new perspective on the interplay between normal state physics and exotic superconducting phenomena in correlated materials.