Electronic structure and phase transition in polar ScFeO3 from first principles calculations

- The properties of ScFeO3 with magnetic ordering are examined by Ab initio method.
- Stability of the polar phase is observed in R3c space group.
- The pressure induced phase transition to non-polar Pnma phase are explained.
- The symmetry mode analysis has been applied to understand polar R3c phase.
- Antiferromagnetic spin structure with spin canting possibility has been studied.

The properties of newly discovered polar ScFeO3 with antiferromagnetic (AFM) ordering are examined using Ab initio calculations and symmetry mode analysis. The GGA + U calculation confirms the stability of polar R3c phase in ScFeO3 and the pressure induced phase transition to non-polar Pnma phase. Octahedron tilting and structural properties as a function of applied pressure have been analyzed. The origin of polar phase is associated with instability of non-polar R3¯c phase and group theory using the symmetry mode analysis has been applied to understand this instability as well as the spontaneous polarization of polar R3c phase. The magnetic phase transition shows G-type AFM ordering of Fe3+ ion with energy scale of ∼200 meV/f.u., which can be understood by Goodenough-Kanamori theory. The magnetic easy axis calculation with spin orbit coupling confirms antiferromagnetic anisotropy in ScFeO3 and spin canting may be realized within ∼0.2 meV/f.u.

(a) Crystal structure and octahedral tilting of ScFeO3 in R3c in [001] projection. Purple big sphere is Sc and red small sphere is Oxygen. (b) Calculated total energy vs. volume in formula unit scale with GGA + U (Fe = 4 eV). (c) Band structure of R3c of ScFeO3 within GGA + U calculation. (d) Energy as a function of spin canting angle between two neighboring spins with opposite directions in the easy axis plane. The data are fitted by polynomial function (solid line).283