A novel near-room-temperature type I multiferroic: Pb(Fe0.5Ti0.25W0.25)O3 with coexistence of ferroelectricity and weak ferromagnetism

Abstract

We report on the crystal structure evolution and the physical properties of the complex perovskite Pb(Fe0.5Ti0.25W0.25)O3. It presents a paraelectric to ferroelectric transition at TC= 293 K, determined by permittivity measurements. The room-temperature neutron powder diffraction pattern (NPD) shows an admixture of the ferroelectric phase (34%, P4mm space group) and the paraelectric polymorph (66%, space group). In both polymorphs the perovskite crystal structure contains the three B cations (Fe, Ti, W) distributed at random at the octahedral sites, and Pb is shifted away from the center of the cubic (sub-)cell. On the other hand, the presence of iron drives the appearance of magnetic interactions above room temperature. This is related to the existence of Fe-rich islands where the strong Fe3+-O-Fe3+ superexchange interactions govern the magnetic behavior. The magnetic structure has been determined from low-temperature NPD experiments as a G-type antiferromagnetic (AFM) cell. Furthermore, there is a net magnetization in the entire range of temperature, which is related to the existence of non-compensated spins in each island. The coexistence of ferroelectricity and a magnetically ordered system, and the observation of a possible coupling between both phenomena allow us to suggest the multiferroic-magnetoelectric nature of the sample.