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

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.KzComment: 30 pages, 13 figure

The preparation, and structural and multiferroic properties of B-site ordered double-perovskite Bi2FeMnO6

“…properties [10][11][12][13][16][17][18][19][20][21][22][23][24][25]. However, experimentally it is hard to achieve the exactly ordered BFMO supercell structure.…”

“…However, experimentally it is hard to achieve the exactly ordered BFMO supercell structure. At present, only disordered BFMO bulk and films, in which Fe and Mn ions are randomly distributed at B sites, have been synthesized, and no convincing experimental evidence for Fe-Mn ordering along [111] direction is found [13,[16][17][18][19]. In addition, recent neutron diffraction experiment further confirmed Fe and Mn disordering at B sites at RT in BFMO epitaxial films [21].…”

Structural and magnetic characterization of the double perovskite Pb2FeMoO6

“…Consequently, the standard procedure applied to describe hyperfine field distribution 24 and the scheme adopted in ref. 25 can be used in the present case. In order to limit the total number of base functions, we introduced only two kinds of clusters and four sub-spectra for each of them, obtaining eight base sub-spectra in total.…”

Oxygen‐vacancy‐controlled magnetic properties with magnetic pole inversion in BiFeO3‐based multiferroics

“…The magnetic pole inversion (or magnetic reversal) is defined as the crossover of DC magnetization from positive to negative as a function of temperature in a magnetically ordered system . Even though this phenomenon is rare, recent studies have revealed the tunable and multiple magnetic pole inversions in multiferroics BiFeO 3 (denoted as BFO) . Due to its high ferroelectric Curie temperature (1103 K) and antiferromagnetic Néel temperature (643 K), BFO is one of the most promising single‐phase multiferroics and has attracted a lot of attention .…”

“…1 Even though this phenomenon is rare, recent studies have revealed the tunable and multiple magnetic pole inversions in multiferroics BiFeO 3 (denoted as BFO). 2,3 Due to its high ferroelectric Curie temperature (1103 K) and antiferromagnetic Néel temperature (643 K), BFO is one of the most promising single-phase multiferroics and has attracted a lot of attention. [4][5][6][7] Notably, the intrinsic defects of oxygen vacancies in BFO can significantly impact its properties, 8 such as changing the fatigue behavior, remnant polarization 9,10 and thermal conductivity, 11 increasing the leakage current, 12,13 and inducing dielectric relaxation and magnetodielectric, 14 weak ferromagnetism, 15,16 and electrochromism.…”