Epitaxial growth and structural characterization of Pb(Fe1/2Nb1/2)O3 thin films

Abstract

a b s t r a c tWe have grown lead iron niobate thin films with composition Pb(Fe 1/2 Nb 1/2 )O 3 (PFN) on (0 0 1) SrTiO 3 substrates by pulsed laser deposition. The influence of the deposition conditions on the phase purity was studied. Due to similar thermodynamic stability spaces, a pyrochlore phase often coexists with the PFN perovskite phase. By optimizing the kinetic parameters, we succeeded in identifying a deposition window which resulted in epitaxial perovskite-phase PFN thin films with no identifiable trace of impurity phases appearing in the X-ray diffractograms. PFN films having thicknesses between 20 and 200 nm were smooth and epitaxially oriented with the substrate and as demonstrated by RHEED streaks which were aligned with the substrate axes. X-ray diffraction showed that the films were completely caxis oriented and of excellent crystalline quality with low mosaicity (X-ray rocking curve FWHMp0.091). The surface roughness of thin films was also investigated by atomic force microscopy. The root-mean-square roughness varies between 0.9 nm for 50-nm-thick films to 16 nm for 100-nmthick films. We also observe a correlation between grain size, surface roughness and film thickness.

Room-temperature single phase multiferroic magnetoelectrics: Pb(Fe, M)x(Zr,Ti)(1−x)O3 [M = Ta, Nb]

“…The room-temperature orthorhombic C 2v point group symmetry inferred from earlier x-ray diffraction studies is confirmed via TEM, and the primitive unit cell size is found to be the basic perovskite Z ¼ 1 structure of BaTiO 3 , also the sequence of phase transitions with increasing temperature from rhombohedral to orthorhombic to tetragonal to cubic mimics barium titanate. It has been known for several years [1][2][3][4][5][6] that the perovskite oxides PbFe 1/2 Ta 1/2 O 3 (PFT), PbFe 1/2 Nb 1/2 O 3 (PFN), and PbFe 2/3 W 1/3 O 3 (PFW) are multiferroics with long-range magnetic ordering near or above room temperature. Our earlier studies showed [7][8][9][10][11][12][13][14][15][16][17] that solid solutions of these materials with PbZr x Ti 1Àx O 3 and pure PbTiO 3 yielded single-phase ferroelectric crystals whose weak ferromagnetism persists to room temperature or above.…”

Room-temperature multiferroic magnetoelectrics

“…Rather surprisingly, recent Russian work by Raevski et al 43 on PFN shows that its relaxor properties are extrinsic. This disagrees strongly with the model of Peng et al…”

“…400 K because of spin clustering. [41][42][43][44] This has been well studied in pure PFN via magnetic resonance. Such cluster systems are not readily amenable via conventional density functional technique theory but might be suited to the type of calculation published by Bersuker and colleagues.…”

Low-temperature neutron diffraction and magnetic studies on the magnetoelectric multiferroic Pb(Fe0.534Nb0.4W0.066)O3

“…Magnetoelectric coupling of PFN can be bettered by tuning its magnetic-order temperature (T N ) by making a solid solution with PFW; however, the microscopic origin of this influence is still unclear. Recently, few efforts have been made to understand the magnetoelectric coupling in PFN [12][13][14]. However, due to its T N being far below room temperature, its practical applications in devices are limited.…”