Thermally activated magnetization reversal in bulk BiFe0.5Mn0.5O3

TL;DR

This study synthesizes bulk BiFe0.5Mn0.5O3, revealing temperature-induced magnetization reversal driven by complex magnetic interactions, with potential implications for multiferroic applications.

Contribution

It reports the first synthesis and detailed magnetic characterization of BiFe0.5Mn0.5O3, demonstrating thermally activated magnetization reversal in a bulk multiferroic compound.

Findings

Magnetization reversal occurs below room temperature.

High magnetic fields suppress the reversal process.

Complex magnetic interactions involve non-equivalent clusters.

Abstract

We report on the synthesis and characterization of BiFe0.5Mn0.5O3, a potential type-I multiferroic compound displaying temperature induced magnetization reversal. Bulk samples were obtained by means of solid state reaction carried out under the application of hydrostatic pressure at 6 GPa and 1100{\deg}C. The crystal structure is an highly distorted perovskite with no cation order on the B site, where, besides a complex scheme of tilt and rotations of the TM-O6 octahedra, large off-centering of the bismuth ions is detected. Below T1 = 420 K the compound undergoes a first weak ferromagnetic transition related to the ordering of iron rich clusters. At lower temperatures (just below RT) two distinct thermally activated mechanisms are superimposed, inducing at first an enhancement of the magnetization at T2 = 288 K, then a spontaneous reversal process centered at T3 = 250 K, finally giving rise to a negative response. The application of fields higher than 1500 Oe suppresses the process, yielding a ferromagnetic like behaviour. The complementary use of SQuID magnetometry and M\"ossbauer spectroscopy allowed the interpretation of the overall magnetic behaviour in terms of an uncompensated weak competitive coupling between non-equivalent clusters of interactions characterized by different critical temperatures and resultant magnetizations. PACS numbers: 75.85.+t, 75.60.Jk, 76.80.+y, 75.30.Et, 75.30.Kz