Materials Literature
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Domain structures in patterned magnetostrictive NixFe1−x films are observed by Kerr microscopy. The micrometer-thick films display different types of domain patterns varying with saturation magnetostriction. In negative magnetostrictive and tensile-stressed films, regular closure domains are replaced by edge curling w…
We report results of thermal expansion (TE) and magnetostriction (MS) measurements on a single crystal sample of Gd5(Si0.5Ge0.5)4 prepared by the Bridgman method. TE and MS were measured along the c axis by the strain gauge method and the temperature was controlled using a closed cycle helium refrigerator. From the TE…
In this study, electron-doped manganese oxide thin films La1−xTexMnO3 (x=0.1,0.15) have been fabricated and their magnetic properties and colossal magnetoresistance effect have been investigated. The experimental results show that the thin films have a high metal–insulator transition temperature TMI of ∼300 K and a la…
The effects of composition and cooling rate on the structure and the magnetic entropy change in Gd5SixGe4−x (x=1.7,2) were investigated. A large magnetic entropy change was obtained in cast and quenched Gd5Si2Ge2, which was attributed to a magnetic field-induced phase transition. This transition is significantly weake…
With the aim of determining and discriminating the influence of both steric and band-filling effects on the strength of the magnetic interactions of double perovskites, we have studied the structural and magnetic properties of substituted LxSr2−xFeMoO6 (L=Ca, La, and Nd) compounds. Our results show that the raising of…
Zinc and niobium doped strontium hexaferrite nanoparticles, Sr(Zn0.7Nb0.3)xFe12−xO19 (x=0–1.0), were fabricated using a sol-gel method for high density magnetic recording. The structure and temperature dependence of magnetic properties are investigated. The experiments show that strontium hexaferrite with small Zn and…
Magnetostriction measurements from 77 K to room temperature on oriented (100) and (110) disk samples of Fe93.9Be6.1 and Fe88.7Be11.3 reveal substantial increases in λ100 compared to iron. For the 11.3% alloy, λ100=110 ppm, a sixfold increase above that of α-Fe. For the 6.1% alloy, λ100=81 ppm, ∼40% and ∼170% greater t…
The wavelength dependence of the quadratic hyperpolarizability of 11 nm diam gold nanoparticles, is reported as measured by hyper Rayleigh scattering. An important photoluminescence background underlying the hyper Rayleigh signal is observed, a contribution attributed to radiative electron-hole recombinations followin…
Co:TiO 2 films were fabricated by laser ablation on Si, LaAlO3 (LAO), and SrTiO3 (STO) substrates from a ceramic target. Films on all types of substrates have Curie temperature (TC) above 400 K. All films are highly crystallized with different structures. While films on Si substrates are rutile, films on LAO and STO s…
The effect of preparation conditions on the structural and optical properties of silicon nanoparticles is investigated. Nanoscale reconstructions, unique to curved nanosurfaces, are presented for silicon nanocrystals and shown to have lower energy and larger optical gaps than bulk-derived structures. We find that high…
A theoretical study based on first-principle band-structure calculations is carried out for the hypothetical semi-Heusler alloys NiVM (M=P, As, Sb, S, Se, and Te). For all compounds it is found that the ferromagnetic state is more favorable than the paramagnetic state. NiVAs is predicted to be a half-metallic ferromag…
Cr-doped reduced-rutile TiO2 thin films were grown on R-plane sapphire substrates by pulsed-laser deposition. X-ray diffraction and transmission electron microscopy results indicate that the films are single phase and reduced-rutile type. Superconducting quantum interference device magnetometer measurements show the f…
We report on the fabrication and electrical characterization of epitaxial Schottky diodes of a half-metallic ferromagnet on an oxide semiconductor. La0.67Sr0.33MnO3 thin films are grown by pulsed laser deposition on niobium-doped SrTiO3 semiconductor substrates with two doping concentrations and a TiO2 surface termina…
We grew Co2(Cr1−xFex)Al Heusler alloy films using a magnetron sputtering system on thermally oxidized Si substrates at room temperature without any buffer layers. The x-ray diffraction patterns did not show the L21 structure as expected for the bulk but revealed the B2 and A2 structures, depending on the Fe concentrat…
Co 2 MnSi Heusler alloy thin films have been grown by cosputtering from three elemental targets. Changes in growth temperature and stoichiometry affect the film texture and the temperature dependence of the resistivity. However, the spin polarization of the transport current is insensitive to these changes, being of t…
Dielectric measurements of the alpha-relaxation time were carried out on a mixture of ortho-terphenyl (OTP) with ortho-phenylphenol, over a range of temperatures at two pressures, 0.1 and 28.8 MPa. These are the same conditions for which heat capacity, thermal expansivity, and compressibility measurements were reporte…
A new method for the parallel fabrication of carbon nanotube (CNT) electronic devices is described. Self‐assembly via magnetic entrapment exploits magnetic fields generated within micrometer‐ or nanometer‐scale devices for the controlled deposition of susceptible species onto predefined contacts (see Figure). The fabr…
The n-type Bi2(Te0.94Se0.06)3 ingots doped with and without 0.010 wt. % CuBr in addition to the codoping of 0.102 wt. % I and 0.026 wt. % Te were grown by the Bridgman method at a rate of 6 cm/h. The thermoelectric properties of these specimens were measured before and after annealing, where annealing was done in the…
We report on measurements of the hole density, ferromagnetic transition temperature TC, and magnetization in a series of as-grown and annealed (Ga,Mn)As samples. Estimating the fraction of incorporated Mn occupying interstitial and substitutional sites allows a direct comparison of the predictions of mean field theory…
The temperature dependencies of the elastic constants of martensitic Ni0.50Mn0.284Ga0.216 were studied in the temperature range from 428 K down to 200 K. Measurements were conducted using the ultrasonic continuous-wave method in a 0.8 T magnetic field. At 220 K abrupt changes were found in the temperature dependences…