Analysis of long-range interaction effects on phase transitions in two-step spin-crossover chains by using Isingtype systems and Monte Carlo entropic sampling technique J. Appl. Phys. 112, 074906 (2012) A-site disorder driven sharp field-induced transition and collapse of charge ordering in Sm1/2Ca1/2-xSrxMnO3 J. Appl. Phys. 112, 073905 (2012) Effect of fast neutron irradiation induced defects on the metamagnetic transition In Ce(Fe0.96Ru0.04)2 J. Appl. Phys. 112, 063922 (2012) Cross-plane electronic and thermal transport properties of p-type La0.67Sr0.33MnO3/LaMnO3 perovskite oxide metal/semiconductor superlattices J. Appl. Phys. 112, 063714 (2012) Experimental evidences of the conservation of the S=1 moment in La2RuO5 determined by perturbed angular correlations J. Appl. Phys. 112, 063915 (2012) Additional information on Appl. Phys. Lett.

Fe-doped ZnO nanocrystals are successfully synthesized and structurally characterized by using x-ray diffraction and transmission electron microscopy. Magnetization measurements on the same system reveal a ferromagnetic to paramagnetic transition temperature above 450 K with a low-temperature transition from the ferromagnetic to the spin-glass state due to canting of the disordered surface spins in the nanoparticle system. Local magnetic probes like electron paramagnetic resonance and Mössbauer spectroscopy indicate the presence of Fe in both valence states Fe 2+ and Fe 3+ . We argue that the presence of Fe 3+ is due to possible hole doping in the system by cation ͑Zn͒ vacancies. In a subsequent ab initio electronic structure calculation, the effects of defects ͑e.g., O and Zn vacancies͒ on the nature and origin of ferromagnetism are investigated for the Fe-doped ZnO system. Electronic structure calculations suggest hole doping ͑Zn vacancy͒ to be more effective to stabilize ferromagnetism in Fe-doped ZnO and our results are consistent with the experimental signature of hole doping in ferromagnetic Fe-doped ZnO samples.

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.

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We have studied the magnetoresistance ͑MR͒ of compressively strained La 0.7 Sr 0.3 MnO 3 ͑LSMO͒ films in various magnetic states in order to understand the role of magnetic domain structure on magnetotransport. In thin films of LSMO on ͑100͒ LaAlO 3 , the perpendicular magnetic anisotropy results in perpendicularly magnetized domains with fine scale ϳ200 nm domain subdivision, which we image directly at room temperature using magnetic force microscopy. The main MR effects can be understood in terms of bulk colossal MR and anisotropic MR. We also find evidence for a small domain wall contribution to the MR, which is an order of magnitude larger than expected from a double exchange model.The doped perovskite manganites have received an enormous amount of attention recently because they exhibit colossal magnetoresistance ͑CMR͒ and may be half metallic, with complete spin polarization at the Fermi level. For these reasons, they may find important uses in magnetoresistive devices, such as magnetic random access memory and sensors. As has been found in magnetoresistive devices based on transition metal ferromagnets, controlling the electronic transport and magnetic properties of these materials in thin film form will be essential to applications. Experimentally, the magnetic and transport properties of colossal magnetoresistance materials have been shown to be highly sensitive to microstructure as well as lattice distortions both in thin film and bulk form. Many groups have shown that properties such as Curie temperature, resistivity and magnetoresistance effect are extremely sensitive to chemical and hydrostatic pressure as well as lattice mismatch with an underlying substrate.1-11 Studies of bulk polycrystalline pellets, thin films of varying polycrystallinity and isolated grain boundaries have shown that the magnetoresistance is profoundly affected by transport across grain boundaries. 2,12,13 Magnetic domain structure may also to lead to distinctive magnetotransport effects in thin films. Mathur et al. report that the measured resistivity of a magnetic domain wall is four orders of magnitude larger than that predicted by a simple double exchange picture.14 Wang et al. have also suggested that large low field magnetoresistance ͑MR͒, in ultrathin compressively strained doped manganite thin films, may be due to domain wall scattering.9 In order to address these questions in LSMO, we have prepared in-plane compressively strained films of LSMO on ͑001͒ LAO (aϭbϭc ϭ3.79 Å) substrates using pulsed laser deposition.9 These films naturally split into stripe domains with length scales set by the strain and film thickness. This enables us to study the effect of magnetic microstructure on MR in a systematic manner. In this letter, we have investigated the magnetics and magnetotransport of epitaxial La 0.7 Sr 0.3 MnO 3 ͑LSMO͒ films. The main MR effects can be explained by CMR and anisotropic MR. We also find evidence for a small domain wall ͑DW͒ contribution to the MR, which is an order of magnitude larger than expected based ...