Revisiting the Structural, Electronic, and Magnetic Properties of (LaO)MnAs: Effect of Hubbard Correction and Origin of Mott-Insulating Behavior.

We study the structural, electronic, and magnetic properties of the antiferromagnetic-layered oxyarsenide (LaO)MnAs system from the first-principle calculation. The increasing Hubbard energy () in the Mn 3d orbital induces the increasing local-symmetry distortions (LSDs) in MnAs and OLa tetrahedra. The LSD in MnAs tetrahedra is possibly promoted by the second-order Jahn-Teller effect in the Mn 3d orbital. Furthermore, the increasing also escalates the bandgap ( ) and the magnetic moment of Mn (μ). The value of = 1 eV is the most appropriate by considering the structural properties. This value leads to and μ of 0.834 eV and 4.31 μ, respectively. The calculated μ is lower than the theoretical value for the high-spin state of Mn 3d (5 μ) due to the hybridization between Mn 3d and As 4p states. However, d states are localized and show the weakest hybridization with valence As 4p states. The Mott-insulating behavior in the system is characterized by the transition between the valence and conduction d /d states. This work shows new physical insights for advanced functional device applications, such as spintronics.