Phase separation in LuFeO3 films

Abstract

The structural transition at about 1000 {\deg}C, from the hexagonal to the orthorhombic phase of LuFeO3, has been investigated in thin films of LuFeO3. Separation of the two structural phases of LuFeO3 occurs on a length scale of micrometer, as visualized in real space using X-ray photoemission electron microscopy (X-PEEM). The results are consistent with X-ray diffraction and atomic force microscopy obtained from LuFeO3 thin films undergoing the irreversible structural transition from the hexagonal to the orthorhombic phase of LuFeO3, at elevated temperatures. The sharp phase boundaries between the structural phases are observed to align with the crystal planes of the hexagonal LuFeO3 phase. The coexistence of different structural domains indicates that the irreversible structural transition, from the hexagonal to the orthorhombic phase in LuFeO3, is a first order transition, for epitaxial hexagonal LuFeO3 films grown on Al2O3

Electronic structure and direct observation of ferrimagnetism in multiferroic hexagonal YbFeO3

“…As shown in Figure 3(a), the spectrum with s-polarized X-ray (E vector in the a-b plane) and that with p-polarized X-ray (E vector along the c axis) show obvious contrast, consistent with the large structural anisotropy. The spectra and linear dichroism in Figure 3(a) match those observed previously for h-LuFeO3, 20,21,33,34 confirming that the local environment of the FeO5 moiety in the two materials are almost identical.…”

Unusual magnetic ordering transitions in nanoscale biphasic LuFeO3: the role of the ortho–hexa phase ratio and the local structure

“…The Raman mapping for both the cases confirms the phase distribution (as established by XRD data refinement), in both the cases and also reveals that both these phases have a phase boundary. 6 Moreover, it indicates that experimental conditions have created favourable conditions for the hexagonal phase of LuFeO3 to grow on the orthorhombic LuFeO3 structure controlling their relative concentration in both the morphologies. 27 Since free energy of formation of o-LuFeO3 is lower than that of h-LuFeO3, this favours the formation of hexagonal phase on the orthorhombic phase to cross the energy barrier over the length scale of submicrometer.…”

“…This is an extraordinary material, which exhibits both orthorhombic (o-) and hexagonal (h-) structures. [5][6][7] There is a significant difference in lattice symmetry and coordination of Fe ion in the case of these o-and h-structures. In o-LFO, ferroelectricity is unexpected due to the symmetry of lattice; while a canting of Fe moments towards c-direction gives rise to weak ferromagnetism below the Neel Temperature (620 K).…”

“…27 Since free energy of formation of o-LuFeO3 is lower than that of h-LuFeO3, this favours the formation of hexagonal phase on the orthorhombic phase to cross the energy barrier over the length scale of submicrometer. 6,7 Table 1. Observed Raman modes in the present study and their one to one comparison with the reported Raman modes for orthorhombic and hexagonal phases, alongwith their designation.…”

Magnetic and dielectric properties of o-LuFeO3/SrTiO3

“…In epitaxial thin films, the film-substrate interfacial energy may favor the h-LuFeO3 structure, if the symmetry of the substrate is triangular or hexagonal. This effect can stabilize the hexagonal structure in epitaxial thin films, to a certain critical thickness [1,4] Therefore, when LuFeO 3 is deposited onto substrate in the form of thin film it can coexist in the form of hexagonal and orthorhombic domains that was established in work [4] where two structural phases of LuFeO 3 occurs on a length scale of micrometer, as visualized in real space using X-ray photoemission electron microscopy, and moreover, there is the structural transition at about 1000 o C, from the hexagonal to the orthorhombic phase of LuFeO 3 [4] and then it results to interesting physical properties.…”