Articles you may be interested inCurrent-sensitive electroresistance and the response to a magnetic field in La 0.8 Ca 0.2 MnO 3 epitaxial thin films J. Appl. Phys. 97, 10H706 (2005); 10.1063/1.1847092 Effects of film thickness and lattice mismatch on strain states and magnetic properties of La 0.8 Ca 0.2 MnO 3 thin filmsThe evolution of three-dimensional strain states and crystallographic domain structures of epitaxial colossal magnetoresistive La 0.8 Ca 0.2 MnO 3 films have been studied as a function of film thickness and lattice mismatch with two types of ͑001͒ substrates, SrTiO 3 and LaAlO 3 . In-plane and out-of-plane lattice parameters and strain states of the films were measured directly using normal and grazing incidence x-ray diffraction techniques. The unit cell volume of the films is not conserved, and it exhibits a substrate-dependent variation with film thickness. Films grown on SrTiO 3 substrates with thickness up to ϳ250 Å are strained coherently with a pure (001) T orientation normal to the surface. In contrast, films as thin as 100 Å grown on LaAlO 3 show partial relaxation with a (110) T texture. While thinner films have smoother surfaces and higher crystalline quality, strain relaxation in thicker films leads to mixed (001) T and (110) T textures, mosaic spread, and surface roughening. The magnetic and electrical transport properties, particularly Curie and peak resistivity temperatures, also show systematic variations with respect to film thickness.

No abstract

Magnetic anisotropy of La0.8Ca0.2MnO3 (LCMO) epitaxial thin films grown on (001) SrTiO3 and LaAlO3 a substrates exhibits strong correlation with substrate-induced strain states as determined by normal and grazing incidence x-ray diffraction. In a 250 Å thick LCMO (001)T film grown on SrTiO3 substrate, an in-plane biaxial magnetic anisotropy is observed, and it is accompanied by a substrate-induced in-plane biaxial tensile strain. In contrast, the observed magnetic easy axis for a 250 Å (110)T film grown on LaAlO3 substrate is perpendicular to the film plane, and the corresponding in-plane strain is biaxial compressive. In both cases the magnetic easy axes are along the crystallographic directions under tensile strain, indicating the presence of a positive magnetostriction. In thicker films (∼4000 Å) grown on both substrates that are nearly strain relaxed, the magnetic easy axis lies in the film plane along the [110] direction of the (001) substrate.

Single domain epitaxial (110) films of SrRuO3 exhibit uniaxial magnetic anisotropy instead of the biaxial anisotropy observed in the bulk material. The magnetic easy axis for the film is along the orthorhombic [010] direction below TC, and it rotates toward the [110] perpendicular direction as temperature decreases. The [100] direction, which is also magnetically “easy” in the bulk, becomes “hard” in the film. X-ray diffraction experiments show that this unique transformation of magnetic anisotropy is related to a distortion from the bulk orthorhombic lattice into a triclinic structure in the epitaxial film, such that the lattice along the [010] direction expands while its [100] counterpart contracts. The distortion appears to arise from rotation and tilt of RuO6 octahedra. The finding indicates that the magnetic anisotropy in epitaxial SrRuO3 films is rooted in the crystalline anisotropy influenced by strong spin–orbit interactions.

Flexible MOFs with a large breathing effect to host hydroxyl compounds for high anhydrous proton conductivity over a wide temperature range.

No abstract

No abstract

The effects of strain relaxation on the crystallographic domain structure and on the magnetic and transport properties of epitaxial colossal magnetoresistive La0.8Ca0.2MnO3 (LCMO) thin films have been studied. LCMO films in the thickness range of 100–4000 Å were grown on (001) SrTiO3 and (001) LaAlO3 substrates, which impose an in-plane tensile and an in-plane compressive biaxial stress in the films, respectively. On (001) SrTiO3 substrates, the films can be grown coherently up to a thickness ∼250 Å, then strain relaxation occurs at a thickness of ∼500 Å. In contrast, even the 100 Å film grown on (001) LaAlO3 is partially relaxed, and the critical thickness for complete strain relaxation is ∼750 Å. The very thin films (<250 Å) show a pure (001)T normal orientation for growth on SrTiO3 and a pure (110)T texture for growth on LaAlO3. As thickness increases, the lattice strain relaxes, resulting in mixed (001)T and (110)T textures for growth on both substrates. Both the Curie and peak resistivity temperatures increase with increasing film thickness, but they do not exhibit a correlation to strain states of the film.