Magnetic ordering and metal-atom site preference in tetragonal CrMnAs: Electronic correlation effects

Area of Science:

• Solid State Physics
• Materials Science
• Computational Materials Science

Background:

• Tetragonal, Cu2Sb-type CrMnAs exhibits complex magnetic ordering.
• Accurate theoretical modeling requires accounting for electron-electron correlations.

Purpose of the Study:

• To investigate the electronic and magnetic structures of CrMnAs using density functional theory.
• To determine the key interactions governing the magnetic ordering in CrMnAs.

Main Methods:

• Density functional theory (DFT) with the Hubbard U (GGA+U) correction was employed.
• Spin-polarized relativistic Korringa-Kohn-Rostoker (SPRKKR) calculations were used to determine exchange parameters.

Main Results:

• Including Hubbard U on Mn atoms was essential for agreement with experimental data.
• Four low-energy antiferromagnetic structures were identified, all sharing similar magnetic interactions.
• One calculated structure matched the experimentally reported magnetic ordering.
• Both direct and indirect exchange couplings significantly influence magnetic properties.

Conclusions:

• The GGA+U approach accurately captures the magnetic behavior of CrMnAs.
• Direct and indirect exchange interactions are critical for understanding the magnetic ordering in this material.