Structural, magnetic, and optical properties ofBiFeO3andBi2FeMnO6

Abstract

BiFeO 3 and Bi 2 FeMnO 6 films were epitaxially grown on SrTiO 3 ͑001͒ substrates by pulsed-laser deposition, and their structural, magnetic, magneto-optical and optical properties were measured. In Bi 2 FeMnO 6 , Fe is mainly present in the 3+ valence state, while Mn shows multivalence states. Bi 2 FeMnO 6 exhibits low magnetization at room temperature and at 5 K indicating there is no significant B-site ordering. The BiFeO 3 film shows high optical transparency, while Bi 2 FeMnO 6 shows high absorption loss in the infrared. Densityfunctional theory modeling of BiFeO 3 , BiMnO 3 and Bi 2 FeMnO 6 was carried out by applying the generalized gradient approximation ͑GGA͒ and GGA+ U methods. The formation enthalpy of ordered Bi 2 FeMnO 6 is positive for several crystal symmetries and for ferromagnetic ͑FM͒ or antiferromagnetic ͑AFM͒ spin structures at 0 K temperature, indicating B-site ordering is not favored. The electronic structure calculations are consistent with the electronic and optical properties of these films.

Spin-cycloid instability as the origin of weak ferromagnetism in the disordered perovskiteBi0.8La0.2Fe0.5Mn0.5O

“…Previous x-ray photoemission spectra and core-level DFT calculations have established both ions predominantly exist in the 3+ state in BiMn 0.5 Fe 0.5 O 3 [44]. DFT calculations in the R3 group for BiFeO 3 found that the local microscopic DM vectors are staggered in such a way that the net DM vector points along one of the (111) directions and has a magnitude that is specified by only two parameters α and β.…”

Interface‐Coupled BiFeO3/BiMnO3 Superlattices with Magnetic Transition Temperature up to 410 K

“…[ 46 ] First of all, according to these rules, most of the possible interactions are AFM (Fe 4+ -O-Mn 3+ , Fe 3+ -O-Mn 2+ , Fe 3+ -O-Fe 3+ , Mn 2+ -O-Mn 2+ , Fe 4+ -O-Mn 2+ ). [ 14,46 ] Also the Fe 4+ -O-Fe 3+ interaction can be expected to be AFM as found in La 1− x Sr x FeO 3 . [ 47,48 ] The presence of these AFM interactions may only decrease the total M S of the superlattices.…”

“…[ 14,19,33 ] The lower M S value of our superlattices is likely to be caused by complex effects resulting from a mixture of AFM and FM ordering which can arise from internal charge transfer leading to mixed ionic valences for Mn and Fe. [ 19 ] Also note that the in-plane BMO/BFO interface is present along the step edges.…”

“…However, this concept has not been widely realized due to the lack of cation ordering as a result of negligible differences in ionic valences and ionic radii. [11][12][13][14][15] On the other hand, disordered double perovskites (notably BiFe 0.5 Mn 0.5 O 3 (BFMO) and Bi 2 CoMnO 6 (BCMO)) show a strongly enhanced T C albeit with lower magnetic moment than expected for the ordered structure. [ 16,17 ] Pálová et al extended the idea of ordered double perovskites by theoretically studying BFMO with an ordered nanoscale checkerboard structure (NCB-BFO/BMO, see Figure 1 a), i.e., columnar B -site ordering.…”

Ultrafast spin polarization in a multiferroic manganite BiFe 0.5 Mn 0.5 O 3 thin film

“…Multiferroic manganite Bi2FeMnO6 (BFMO), a compound of BiFeO3 and BiMnO3, has been recently designed theoretically and fabricated experimentally. More intense research has resulted in promising findings such as multiferroic, coexisting a small net ferromagnetic magnetization at room temperature and ferroelectricity at low-temperature in BFMO [5][6][7]. In the previous work, based on the small magnetic moment observed in M-H loop, Mn-O-Mn is antiferromagnetically ordered in BFMO, which is much weaker than Fe-O-Fe ordering [8].…”