Polar P6₃cm phase as a marginally stable ground-state structure of InMnO₃: First-principles study

¹ Department of Materials Science and Engineering, and Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH) - Pohang 790-784, Republic of Korea
² Department of Materials Science and Engineering, Massachusetts Institute of Technology (MIT) Cambridge, MA 02139, USA

Received: 3 December 2013
Accepted: 3 December 2013

Abstract

To resolve a dispute associated with the ferroelectricity in hexagonal InMnO₃ (h-IMO), we have examined the ground-state structure by exploiting density-functional theory calculations. It is shown that the ferroelectric phase is marginally stable over the nonpolar phase for a wide range of the external pressure. However, the computed Kohn-Sham energy predicts an interesting crossover from the polar state to the nonpolar state beginning at a compressive strain of ∼1%. The partial density of states (PDOS) supports our previous finding that the In 4d-O 2p hybridization is the main bonding mechanism directly related to the manifestation of ferroelectricity in h-IMO. In addition, the computed PDOS does not show any evidence of the In 5s-O 2p orbital overlapping which had been asserted to be the main bonding interaction in the nonpolar phase.