Structural and magnetic properties of stable hexagonal TmFeO3 ceramics with In doping

Abstract

Hexagonal rare-earth ferrites (h-RFeO₃) is a promising multiferroic materials with strong magnetoelectric coupling effect by tuning the collective tilt of FeO₅ trigonal bipyramids. However, the metastable hexagonal structure for RFeO₃ bulk materials is still pain point that needs to be solved. In this work, multiferroic h-RFeO₃ ceramic materials were designed and prepared by doping TmFeO₃ ceramics with In, which were fabricated by using the standard solid-state sintering method. Stable h-Tm_1−xIn_xFeO₃ (x = 0.6, 0.7) ceramics crystallized into a pure hexagonal structure with the polar space group P6₃cm (x = 0.6) and the non-polar space group P6₃/mmc (x = 0.7) at room temperature. Two magnetic transitions were identified in the ceramic samples, a paramagnetic to antiferromagnetic transition (T_N), and spin reorientation transition (T_SR). The dielectric anomalies were observed around the spin reorientation temperature (T_SR), which indicates significant magnetoelectric coupling effects in the h-Tm_1−xIn_xFeO₃ (x = 0.6, 0.7) ceramics. Furthermore, using dielectric and pyroelectric characterization techniques, dielectric peaks were observed near 280 K for the x  = 0.6 sample, which should be a weak structural transition through the analysis of XRD patterns at various temperatures. The presence of stable hexagonal structure for In-doping TmFeO₃ is enlightening the multiferroic materials in hexagonal ferrites.