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We report on epitaxial thin films of spinel ferrite Ni0.65Zn0.35Fe1.2Al0.8O4 with strain-induced perpendicular magnetic anisotropy (PMA) and low magnetic damping. Static magnetometry and broadband ferromagnetic resonance experiments show a distinct change in the preferred direction of magnetization from in-plane to out-of-plane when the coherent strain in films changes from ∼2% compressive on (001) MgAl2O4 to ∼0.5% tensile on (001) MgGa2O4 substrates. Significant deviations from the spin-only value (2.0) of the g-factor suggest spin-orbit effects and further support our conclusion of strain-driven magnetic anisotropy in these films. The low Gilbert damping parameter of α = 5 × 10−3 in these ferrite films, combined with their PMA, makes them promising for spintronic and frequency-agile microwave device applications. [ABSTRACT FROM AUTHOR]

We report the influence of in-plane strain on uniaxial magnetic anisotropy of Co2(Fe/Mn)Si [CF(M)S] films grown on SrTiO3 (STO) and MgO by varying film thickness. The analysis of magnetic free energy functional for the films on STO showed the presence of magnetoelastic anisotropy with magnetostriction constant of 12.22×10-6 for CFS and 2.02×10-6 for CMS in addition to intrinsic magnetocrystalline anisotropy. Single-domain phase diagram reveals a gradual transition from in-plane to canted state with decreasing film thickness due to strain-induced tetragonal distortion. A maximum canting angle of 41.5° with respect to film plane is predicted for CFS (12 nm)/STO film. [ABSTRACT FROM AUTHOR]

We have utilized the antiferromagnetic nature and structural/chemical compatibility of La0.45Sr0.55MnO3 with highly spin polarized La0.67Sr0.33MnO3 to prepare epitaxial exchange bias (EB) couples. A robust EB shift in magnetization hysteresis with associated interfacial exchange energy J≈0.13 erg/cm2 at 10 K along with enhanced coercivity is reported. The EB effect was engineered to bring coercivity contrast between La0.67Sr0.33MnO3 and cobalt films in La0.45Sr0.55MnO3/La0.67Sr0.33MnO3/SrTiO3/Co magnetic tunnel junctions. [ABSTRACT FROM AUTHOR]

High coercivity nanoscale structures of CoPt are grown on (001) SiTiO3 with pulsed laser ablation. At low growth rate (≃0.4 Å/s), the film morphology changes from a self-similar fractal to nanodots as the deposition temperature is raised from 700 to 800 °C. While the nanodots are L10 ordered phase with out-of-plane c axis and coercivity Hc⊥≃30 kOe, the fractals have a nonzero, in-plane c-axis component of the L10 phase. The large lattice mismatch between (001) SrTiO3 and the ac/bc plane of L10 imparts tensile strain to the films whose morphological manifestations can be suppressed at high growth rates. [ABSTRACT FROM AUTHOR]

YBa2Cu3O7–La2/3Sr1/3MnO3heterostructures of [110] orientation are grown to allow direct injection of spin polarized holes from the La2/3Sr1/3MnO3 into the CuO2 superconducting planes. The magnetic response of the structure at T≤sTsc shows both diamagnetic and ferromagnetic moments with [001] direction as magnetic easy axis. While the superconducting transition temperature (Tsc) of these structures is sharp (ΔTsc≃2.5 K), the critical current density (Jc) follows a dependence of the type Jc=Jo(1-T/Tsc)3/2 with highly suppressed Jo(≃2×104 A/cm2), indicating strong pair breaking effects of the ferromagnetic boundary [ABSTRACT FROM AUTHOR]

Measurements of the critical current density (J[sub c]) and irreversibility field [B[sub irr](T)] of epitaxial, c-axis-oriented EuBa[sub 2]Cu[sub 3]O[sub 7] (Eu-123) films are reported. The transition temperature (T[sub c]), J[sub c], and B[sub irr](T) of these pulsed-laser-deposited films depend critically on the growth temperature (T[sub D]), growth rate (G[sub r]), and the oxygen partial pressure (pO[sub 2]) during growth. As compared to YBa[sub 2]Cu[sub 3]O[sub 7], Eu-based films require lower G[sub r], higher pO[sub 2], and higher T[sub D]. These differences are attributed to the lower adatom mobility of Eu and its propensity for a 2+ oxidation state. The lattice mismatch between (100) LaAlO[sub 3] and the ab-plane of Eu-123 leads to an elongated c axis and some randomly oriented islands whose growth is truncated by epitaxial lateral overgrowth as the film thickness increases. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The use of rf excited oxygen plasma for oxidizing and possible etching of SrTiO3 (100) supported Y2Ba4Cu8O16 thin films is studied by photoemission. Oxygen plasma modifies the surface and eliminates photoemission features identified with surface impurities like BaCO3. The resulting surface is barium deficient but shows a Fermi level suggesting it is metallic. Application of a -200 V dc bias to the sample to increase the kinetic energy of the incident oxygen ions enhances either surface sputtering or atomic mixing and produces a surface which resembles YBa2Cu3O7, because the photoemission spectra are similar to those published for cleaved crystal surfaces or films. [ABSTRACT FROM AUTHOR]

Infrared absorption measurements and the temperature dependence of stress have been used to establish the kinetics of structural relaxation and hydrogen evolution from plasma deposited a-SixNy :H films. The Arrhenius rate law describes the dissociation of N–H and Si–H bonds which occurs on annealing the films above 600 °C. The activation energies deduced from the infrared data are lower than the respective bond dissociation energies. The films undergo a rapid stress relaxation in the temperature range 400–650 °C. The discussion of the experimental results highlights possible mechanisms for the evolution of hydrogen from a-SixNy[ATOTHER]@B:[/ATOTHER]H networks. [ABSTRACT FROM AUTHOR]

A screen printing method has been used to deposit superconducting films of Y-Ba-Cu-O materials on Al2O3 substrates. The electrical resistivity, microstructure, and adhesion of these films are highly sensitive to the post-printing heat treatment. Films heat treated at 950 °C and below are poorly adherent, whereas those annealed above 1000 °C undergo phase separation to Y2Cu2O5 and BaCuO2 and also react with the substrate. Nearly single phase, highly adherent, and smooth films showing a zero resistance state at 79 K have been synthesized by optimizing the annealing conditions. [ABSTRACT FROM AUTHOR]

Direct evidence of substitutional doping of nitrogen in ion beam deposited hydrogenated amorphous silicon, from analysis of infrared spectra and Si-2p core level shape measured with x-ray photoelectron spectroscopy (XPS), is presented. For the first time the XPS technique has been used to deduce the upper limit for substitutional solid solubility of the impurity. [ABSTRACT FROM AUTHOR]