Unique Crystal Structure of Ca_{2}RuO_{4} in the Current Stabilized Semimetallic State

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Calcium Ruthenate (Ca_{2}RuO_{4}) is a quasi-two-dimensional Mott insulator.
• It exhibits unusual electronic properties under specific conditions.

Purpose of the Study:

• To investigate the nature of the electric-current stabilized semimetallic state in Ca_{2}RuO_{4}.
• To understand the origin of its strong diamagnetism and distinct crystal structure.

Main Methods:

• Neutron and X-ray diffraction for structural analysis.
• Dynamical Mean Field Theory (DMFT) calculations for electronic structure.
• Crystallographic refinement and Coulomb repulsion parameter estimation.

Main Results:

• A novel nonequilibrium semimetallic phase in Ca_{2}RuO_{4} stabilized by electric current.
• This phase possesses a unique crystal structure and electronic band structure, distinct from equilibrium metallic phases.
• DMFT calculations reveal a semimetallic state with a partially gapped Fermi surface.
• Antiferromagnetic long-range order is completely suppressed in this nonequilibrium state.

Conclusions:

• The study elucidates the distinct structural and electronic properties of the nonequilibrium semimetallic state in Ca_{2}RuO_{4}.
• Findings provide a foundation for theoretical exploration of the anomalous diamagnetism in this material.