Spin frustration and spin-lattice coupling in multiferroic hexagonal HoMnO3 investigated by the first principles

Based on density functional theory, the spin frustration and the spin-lattice coupling in hexagonal HoMnO3 are investigated. By comparing the different lattice geometry of antiferromagnetic, noncollinear Γ1 and Γ4 structure, we show that the ionic position in the unit cell, the bond length, the distribution of electronic structures have a significant correlation with frustrated magnetic structures. The strong orbital hybridizations of Ho 5dz2-O(3,4) 2pz and Mn 3 dxy,x2−y2-O(4)2px,y states modify the strength of the bonds and hold the key to spin-lattice coupling and lattice distortion. All these provide theoretical support for the explanation of the magnetoelectric phenomenon in HoMnO3.