Materials Literature
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Light-induced anchoring of the molecular director is reported to be an efficient method for writing permanent holographic gratings in dye-doped liquid crystals. We have achieved higher sensitivity and spatial resolution in these materials with other methods. An energy density as low as 10(-1) J/cm(2) was sufficient to…
We have deposited epitaxial diamond films with very low angular spread on epitaxial β-phase silicon carbide layers on silicon (001) substrates. From x-ray rocking curve measurements, half-widths of the angular spread of the crystal orientation as low as 0.6° have been determined, which is the smallest value ever repor…
A three-dimensional (3D) rewritable optical memory using photochromic material is described for high-density memory. The bits are recorded in a 3D volume of photochromic material. A transformation of the photochromic molecule between two isomers with different absorption spectra can be stimulated by irradiation with a…
The multilayer thin films having the form of Ti(30 nm)/Fe(dFe)/[Nd–Fe–B(dNd–Fe–B)/Fe(dFe)] ×5/Ti(30 nm)/glass were fabricated on glass substrates by means of radio frequency (rf) sputtering, with dFe varied from 0 to 50 nm and dNd–Fe–B from 0 to 100 nm. Magnetization measurements have revealed that the minor loops of…
In this work polycrystalline perovskite with composition La0.7Ca0.3Fe0.05Mn0.95O3 has been produced by standard ceramic method. A considerable change occurs in magnetic, transport and magnetoresistance properties with respect to the classic composition without Fe. The introduction of a different metal, Fe, in Mn-O lay…
A thorough study of the Mössbauer spectra (MS) of a lightly iron doped (2%) polycrystalline La0.75Ca0.25MnO3 compound has been carried out from T=4.2 K up to 300 K. The MS for T>Tc and at T=4.2 K show one component. The corresponding hyperfine parameters are compatible with S=5/2 Fe3+ in octahedral coordination…
We present angle-resolved photoelectron spectra and surface state dispersions for the clean, 2\ifmmode\times\else\texttimes\fi{}1 reconstructed (111) and (100) surfaces of diamond. For the (100) surface a surface state is found in the gap of the projected bulk band structure around Y-bar, which has a binding energy of…
We present a theoretical study of the magnetic polaron associated with an electron-hole pair in a diluted magnetic semiconductor quantum dot. It is based on the effective-mass approximation in the strong confinement regime, which incorporates the coupling between the light- and heavy-hole bands. The magnetic polaron,…
We report on the metal-insulator transition of La0.5Sr0.5CoO3 thin films deposited by pulsed laser ablation on LaAlO3 substrates. The films were cooled in oxygen partial pressures between 760 and 10−5 Torr and electrical resistivity of the films was measured as a function of cooling oxygen pressure. La0.5Sr0.5CoO3 fil…
The results of low-temperature, ultrahigh-resolution ultraviolet photoemission studies of the electronic structure of stable icosahedral ${\mathrm{Al}}_{65}$${\mathrm{Cu}}_{20}$${\mathrm{Fe}}_{15}$, ${\mathrm{Al}}_{64}$${\mathrm{Cu}}_{24}$${\mathrm{Fe}}_{12}$, ${\mathrm{Al}}_{65}$${\mathrm{Cu}}_{20}$${\mathrm{Ru}}_{15…
Charge-ordered stripes in La1−xCaxMnO3 with x>0.5 were studied by electron diffraction and electron microscopy. Charge-ordered domains were observed in dark-field images and the stripes within the domain were revealed by high resolution lattice images. The modulation wave vector δ of the charge ordering follows…
Lifetimes of hot electrons in the 1.3--3.2-eV energy range at low index surfaces of Cu((100),(110),(111)) are measured by two-photon time-resolved photoemission spectroscopy with 10 fs resolution. Energy dependence of the lifetimes deviates from the (E-${\mathrm{E}}_{\mathrm{F}}$${)}^{\mathrm{\ensuremath{-}}2}$ functi…
The determination of the magnetic properties of antiferromagnetic Cr alloys requires careful consideration of the influence of the applied magnetic field. In this work we show that alloys of Cr-x at. % V present a Curie–Weiss paramagnetism above the Néel temperature, which is suppressed by a characteristic field HL. S…
NbFeTe 2 is a layered cluster compound in which intra Fe–Fe bond distance is 2.488 Å. The magnetic susceptibilities between 100 and 300 K are fit to Curie–Weiss law with C=1.29 emu K/mol, and θ=+69.2 K. The effective magnetic moment of 3.67 μB per Fe at 300 K corresponding to three unpaired electrons may suggest the f…
An extension to the model of hysteresis has been presented earlier which included the effect of anisotropy in the modeling of the anhysteretic magnetization curves of uniaxially anisotropic single crystalline materials. Further exploration of this extension shown here considers different kinds of crystal anisotropy in…
The MnAl-base permanent magnets continue to loom on the horizon as potentially important technological materials. Marginal enhancement of their technical magnetic properties and improved processing could markedly change the relationship of these materials to the current market. MnAl-base magnets derive their attractiv…
The origin of coercivity in precipitation hardened Sm–Co magnets is investigated. By considering domain-wall pinning at boundary phase and Z phase inhomogenities, it is found that the hexagonal Z phase has no direct influence on the coercivity. The intuitive assumption of plane domain walls made in a recent calculatio…
Bonded neodymium magnets can provide significant size and weight reduction and/or performance enhancement over sintered and, particularly, bonded ferrite permanent magnets and, moreover, provide these benefits at reasonable cost. Primarily for these reasons, these bonded magnets are now used in a wide and growing rang…
FeSe thin films were prepared on GaAs(100) substrate by the selenization of Fe films using molecular-beam epitaxy. FeSe compound thin films were obtained at a substrate temperature above 380 °C. From the depth profiles of Fe and Se in the selenized film measured by Auger electron spectroscopy, it was confirmed that an…
Ferromagnet-insulator-ferromagnet tunnel junctions with one NiMnSb electrode were studied to test the 100% conduction electron spin polarization predicted from band structure calculations performed on this compound. This phenomenon, known as half-metallic ferromagnetism (HMF), should result in significantly larger jun…