Semimetallic spin-density wave state in iron pnictides.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Solid-State Physics

Background:

• Iron pnictides exhibit metallic spin-density wave (SDW) states with Fermi pockets.
• Symmetry-protected Dirac cones are observed away from the Fermi surface in these states.

Purpose of the Study:

• To investigate the conditions for realizing semimetallic spin-density wave (SDW) states in iron pnictides.
• To understand the role of orbital splitting on Dirac points and Fermi pockets.
• To explore topologically protected edge states in ribbon geometries.

Main Methods:

• Theoretical analysis of electronic band structures.
• Examination of orbital splitting effects on Dirac cone location.
• Study of band slopes and orbital contents.
• Investigation of ribbon geometries for edge state analysis.

Main Results:

• Orbital splitting significantly influences the position of Dirac points relative to the Fermi surface.
• Fermi pockets unrelated to Dirac cones can be suppressed by orbital splitting, enabling semimetallic SDW states.
• Conditions for coexisting Dirac semimetallic and SDW states were determined based on band properties.
• Topologically protected edge states were analyzed in both x and y oriented ribbon geometries.

Conclusions:

• Orbital splitting is a key factor in realizing semimetallic SDW states in iron pnictides.
• The findings provide a framework for understanding the interplay between electronic structure, magnetism, and topology.
• The study offers insights into the design of materials with specific electronic and topological properties.