The Optical and Ferroelectric Properties of Fe-Doped Hybrid Improper Ferroelectricity Ca3ti2o7 Via Experimental and Density Functional Theory Study

Abstract

The magnetoelectric multiferroic materials with ferroelectric and magnetic orders have great attributed attention in the field of magnetoelectric memories and magnetic resonance devices. Here, we systematically investigated the optical and multiferroic properties of Fe-doped hybrid improper ferroelectricity Ca3Ti2O7 prepared by sol-gel method. The distortion of TiO6 octahedron increases with the increase of Fe doping concentration, resulting in an increasing of remnant ferroelectric polarization. The slight blue shift of the Raman band at 667cm-1 is attributed to the introduces of oxygen vacancies by Fe doping. With the introduces of Fe3+, the magnetism increases gradually. The first-principles calculation shows that magnetism origins from the low spin state of Fe-3d and their surrounding O-2p orbitals. Ca3Ti1.9Fe0.1O7 with large polarization strength and magnetic moment is expected to be applied in magnetoelectric memories and sensors, spintronics and magnetic response devices.

Keywords: Fe-doped Ca3Ti2O7, Sol-gel method, Ferroelectricity, oxygen vacancy