Microscopic mechanisms for phase coexistence and electric polarization enhancement in Mn1−xIrxWO4 + δ.

We investigate the magnetic and ferroelectric behaviors of 5d Ir⁴⁺ substituted Mn_1−xIr_xWO_{4+ δ} samples. The electric polarization is enhanced to a certain extent due to the Ir substitution of Mn. Furthermore, the non-polar AF1 phase is partially suppressed by the ferroelectric AF2 phase, resulting in the coexistence of the two phases below T_AF1. It is suggested that the lattice distortion, the suppressed magnetic moment, and the increased Dzyaloshinskii–Moriya interaction are the key reasons for the enhanced polarization and the stabilized ferroelectric AF2 phase. [ABSTRACT FROM AUTHOR]