Structural and electrical properties of LuMnO3 thin film prepared by chemical solution method (original) (raw)
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Epitaxial thin films of half-metallic oxide La0.7Sr0.3MnO3 (LSMO) have been grown in two crystalline orientations, one with the c-axis out-of-plane, the (001) orientation, and one with the c-axis in-plane, the (110) orientation. For the (110) oriented growth, there is no polar discontinuity at the substrate–film interface and hence no dead layer formation, which improves ferromagnetic interaction in the LSMO, making it highly attractive for spintronic applications. In our experiments, with x-ray diffraction, x-ray photoelectron spectroscopy and magnetic measurements, we have demonstrated that in the (110) oriented LSMO the lattice is more relaxed, leading to less deformation of electronic density around the La atom or in the MnO6 octahedra. This improved crystal and electronic structure improves the ferromagnetic properties of the films, making the Curie temperature higher by almost 15 K, which is of potential interest for spintronics. However, substrate strain induced magnetic anisotropy causes domain formation with out-of-plane components in these films, which poses some concern for practical spintronic devices.
Crystal structure, magnetic and dielectric behavior of h-LuMn x O 3 7 δ ceramics (0.95 rx r1.04
Lattice constants, magnetic properties and dielectric behavior of h-LuMn x O 3 7 δ solid solution (0.95 rx r1.04) of bulk ceramic samples prepared by the solid state reaction method were studied to determine the role of stoichiometry changes on the crystalline structure and magneto-electric coupling. It is found that increasing of Mn content results in reduction of cell volume of h-LuMn x O 3 7 δ ceramics mostly due to shrinkage of a-axis length. The antiferromagnetic interactions of Mn 3 þ ions weaken with cell volume contraction. A weak ferromagnetic contribution appeared in all samples and extends up to the Neel temperature, T N. Irreversibility in temperature dependent magnetic measurements already reported for stoichiometric compositions of hexagonal RMnO 3 oxides appears for all h-LuMn x O 3 7 δ samples right below Neel ordering transition. An increase of magnetic coercive field and magnetization on cooling below T N in samples is observed in field dependent magnetization and rises as x increases. In addition to the antiferromagnetic ordering transition at T N , two anomalies of the temperature dependent magnetic susceptibility and dielectric constant are identified below T N , centered at 69 K and 31 K respectively , being probably due to inhomogeneity of the crystalline structure inside ceramic grains. Changes of the dielectric constant at T N can be attributed to magneto-electric coupling in the off-stoi-chiometric hexagonal LuMn x O 3 7 δ lattice. The behavior of the dielectric relaxation follows a thermally activated mechanism with activation energy values characteristic of polaron hoping.
Journal of Alloys and Compounds, 2013
A novel method, ultra-high pressure sintering (UHPS), for preparing highly-dense La 2 NiMnO 6 (LNMO) ceramic at a ultra-high pressure (4 GPa) and a low sintering temperature (800 °C) over a short duration (10 min) had been developed. TEM images and Rietveld fitted XRD patterns confirmed the coexistence of monoclinic P2 1 /n and hexagonal R3 _ phases in the ceramic. Compared with the samples prepared by conventional sintering, the grain size of the LNMO ceramic obtained by UHPS was remarkably decreased (from 3-10 µm to 300-500 nm) while the relative density was increased significantly (from 65-95% to 98.5%), which could be attributed to the unique UHPS sintering process. It was further noted that the ferromagnetic-paramagnetic transition temperature (T C1 ≈ 277 K) as well as the saturation magnetization (M s ≈3.6 µ B /f.u.) were improved due to the denser structure and smaller grain size, as compared with the conventionally sintered LNMO samples.
Magnetic transition anisotropies in orthorhombic LuMnO 3 and HoMnO 3 multiferroic thin films
Journal of Physics: Conference Series, 2010
We have successfully prepared the b-axis-oriented orthorhombic LuMnO 3 (LuMO) and HoMnO 3 (HMO) thin films by pulsed laser deposition on (110)-LaAlO 3 substrates. The nearly perfect alignment between the film growth orientation and the substrate allows us to study the magnetic transitions along the respective crystal orientation, which has displayed marked anisotropic behaviours. In particular, with the largest ionic size difference between Lu and Ho for the family of RMnO 3 displaying the E-type AFM, the effects of lattice distortion on the magnetic transition are compared.
We report the magnetic susceptibility, specific heat and dielectric constant on high purity polycrystalline samples of three hexagonal manganites: YMnO_3, LuMnO_3 and ScMnO_3. These materials can exhibit a ferroelectric transition at very high temperatures (T_{FE} > 700K). At lower temperatures there is magnetic ordering of the frustrated Mn^{3+} spins (S=2) on a triangular Mn lattice (YMnO_3:T_N=71K; LuMnO$_3:T_N=90K and ScMnO_3:T_N=130K). The transition is characterized by a sharp kink in the magnetic susceptibility at T_N below which it continues to increase due to the frustration on the triangular lattice. The specific heat shows one clear continuous phase transition at T_N, which is independent of external magnetic field up to 9T with an entropy content as expected for Mn^{3+} ions. The temperature dependent dielectric constant displays a distinct anomaly at T_N.
Interface magnetic properties of La0.7Sr0.3MnO3 thin films
Journal of Magnetism and Magnetic Materials, 2004
Magnetic properties of La 0:7 Sr 0:3 MnO 3 thin films with various capping layers have been investigated by SQUID magnetometry and X-ray magnetic circular dichroism. Results on the temperature dependence of the magnetization, orbital to spin moment ratios and the magnetocrystalline anisotropy are presented.
Investigation of Stereometric and Fractal Patterns of Spin-Coated LuMnO3 Thin Films
Advances in Materials Science and Engineering
In this paper, we have performed qualitative and quantitative analysis of LuMnO3 thin films surfaces, deposited by spin coating over Pt(111)/TiO2/SiO2/Si substrates, to evaluate their spatial patterns as a function of the film’s sintering temperature. Atomic force microscopy was employed to obtain topographic maps that were extensively analyzed via image processing techniques and mathematical tools. 3D (three-dimensional) topographical images revealed that films sintered at 650°C and 750°C presented the formation of smoother surfaces, while the film sintered at 850°C displayed a rougher surface with a root mean square roughness of ∼2.5 nm. On the other direction, the height distribution of the surface for all films has similar asymmetries and shape, although the film sintered using the highest temperature showed the lower density of rough peaks and a sharper peak shape. The advanced fractal parameters revealed that the film sintered at 850°C is dominated by low spatial frequencies, ...
Influence of magnetic on ferroelectric ordering in LuMnO3
Physical Review B, 2004
We have studied the influence of antiferromagnetic ordering on the local dielectric moments of the MnO 5 and LuO 7 polyhedra by measuring neutron powder-diffraction patterns of LuMnO 3 at temperatures near T N . We show that the coupling is weak, because the magnetic exchange coupling is predominantly in the ab plane of the MnO 5 trigonal bipyramids, and the electric dipole moments, originating in the LuO 7 polyhedra, are oriented along the hexagonal c axis. Anomalies in the dielectric properties near T N are thus caused by the geometric constraints between the MnO 5 and the LuO 7 polyhedra.
Magnetic and structural studies of LaMnO 3 thin films prepared by atomic layer deposition
Journal of Physics D: Applied Physics, 2013
Here we report the results of structural, microstructural and magnetic property characterizations of both thin films and bulk samples of LaMnO 3 (LMO). Thin films were deposited by the atomic layer deposition technique on silicon (1 0 0) substrates, whereas bulk samples were prepared by a citrate combustion route. Effects of varying thickness, annealing atmosphere and temperature were studied on both LMO sample classes. Single-phase perovskite crystal structure was confirmed by x-ray diffraction and Raman spectroscopy, in thin films annealed at 700 and 800 • C as well as in bulk samples. Thin films annealed in N 2 or O 2 atmosphere do not vary in the crystal structure, but differ by the oxygen stoichiometry, microstructure and magnetic properties. The Curie temperature in all LMO thin films annealed in N 2 was found to be around 200 K, while it was around 250 K for the films annealed in O 2 as well as for the bulk samples.
2005
Fe-Co-Cr and Fe-Co-Cr-N thin films were fabricated by magnetron co-sputtering at room temperature, and their structural, electrical and magnetic properties were examined by various analytic techniques. It was observed that with the increase of Cr-target power, for Fe-Co-Cr thin films the resistivity increased and surface morphology was changed. As the nitrogen gas flow ratio increased, for Fe-Co-Cr-N thin films the grain size decreased and the resistivity monotonically increased. Fe-Co-Cr thin films exhibited the best soft-magnetic properties with a relatively large saturation magnetization (M s ) of 1.77 Wb/m 2 and a small coercivity (H c ) of 748 A/m at a Cr-target power of 80 W, whereas Fe-Co-Cr-N thin films had the best soft-magnetic properties with a high saturation magnetization (M s ) of 1.64 Wb/m 2 and a minimum coercivity (H c ) of 279 Wb/m 2 at a nitrogen gas flow ratio of 20%. The grain refinement mechanism of chromium and nitrogen in the FeCo-based films was also discussed.