Observation of a new cryogenic temperature dielectric relaxation in multiferroic Bi7Fe3Ti3O21

Abstract

In this communication, we report details of structural, magnetic, and dielectric properties of multiferroic Bi7Fe3Ti3O21 at cryogenic temperatures. The low temperature impedance spectroscopic studies showed a relaxor-like dielectric anomaly which follows Vogel-Fulcher relation with freezing temperature (TVF) of 33 K. Temperature and field dependent magnetization indicate the onset of a possible antiferromagnetic ordering below 150 K. Variable temperature powder neutron diffraction studies indicate no structural change down to 22 K. The appearance of the low temperature dielectric anomaly along with evidence of magnetic ordering at low temperatures suggests the presence of magnetic domains of mesoscopic scale within the bulk matrix.