Evidence of the Griffiths phase in multiferroic BiMnO3 and BiFe0.5Mn0.5O3 films

Abstract

Microstructure and magnetic properties of the BiMnO 3 and BiFe 0.5 Mn 0.5 O 3 films, prepared by the rf magnetron sputtering on LaAlO 3 (001) single-crystalline substrate, have been investigated. The selected-area electron diffraction analysis allows us to indentify the crystal structure of the BiMnO 3 film as an orthorhombic one while the BiFe 0.5 Mn 0.5 O 3 film has a hexagonal lattice symmetry. The high-resolution electron microscopy study reveals the presence of strip-domain phase with a periodic spacing of about 3c in both films. The magnetic measurements show that in addition to the basic paramagnetic phase, the films manifest the Griffiths phase behavior in a wide temperature range. We argue that the observed weak ferromagnetism is provided by an appearance of the strip-domain layered inclusions rather than the intrinsic physical origin of the films.

Room Temperature Ferrimagnetism and Ferroelectricity in Strained, Thin Films of BiFe0.5Mn0.5O3

“…Now we discuss the possible origin of the high T C FIM phase in disordered, highly strained, crystalline BFMO. First we note that transition metal perovskites show a great sensitivity of properties to bond angles and bond lengths . As already mentioned, one of three strain mediated mechanisms can explain the behavior observed.…”

“…Hence it is understandable why previously studied thicker films from the literature had very small or zero moments, e.g., a 180 nm thick film with a c‐ axis of 3.952 Å had an M S value of 4 emu/cc at RT and 1.5 T . The magnetic moments for the most strained films of our study (<70 nm) are around an order of magnitude higher than literature values of thicker (>100 nm) BFMO films . On the other hand, the values are around 30% lower than the best values (90 emu/cc) we obtained for ∼30 nm films on higher quality pure STO substrates (FWHM values of ω ‐rocking curve of (002) peak of 0.019° and (103) peak of 0.03°) where there is better epitaxy than on Nb:STO (FWHM values of ω ‐rocking curve of (002) peak of 0.023° and (103) peak of 0.10°), but it was necessary to use the Nb:STO conducting substrates in this work to measure FE properties .…”

“…As far as Mn doping of the B ‐site goes, even though the theoretical predictions of Pálová et al suggested that it may be possible to achieve co‐existent FM and FE, in both bulk and thin films over a wide doping range only low moments have been observed . However, in these earlier studies relatively thick films (>100 nm) were studied which were not highly strained …”

Exchange-spring mechanism and Griffiths-like phase in room-temperature magnetoelectric Ni–BaTiO3 composites

“…In 2012, Prokhorov et al reported GP in single-phase multiferroic BiMnO 3 and BiFe 0.5 Mn 0.5 O 3 films. 26 Later, Singh et al reported GP in a manganese doped Co 3 TeO 6 multiferroic. 27 Due to the highly conducting nature, ME structures involving 0D and 1D…”

Influence of LaNiO3 and LaNi0.5Mn0.5O3 Buffer Layers on the Structural and Electrical Properties of BiNi0.5Mn0.5O3 Thin Films

“…These results suggest a polycrystalline hexagonal perovskite structure in space group P63cm. [19][20][21][22] The crystal structure in BNM film is different from that in bulk BNM. This may be ascribed to the effect of interface, especially in thin films.…”