Neutron reflectivity from annealed thin films of the poly(styrene-b-deuterated methylmethacrylate), P(S-b-D-MMA), reveals formation a multilayered morphology parallel to film surface. This multilayer forms so that PS locates, preferentially, at air/copolymer and D-PMMA substrate/copolymer interfaces with layer thicknesses these one-half found in bulk. P(D-S-b-MMA) lower molecular weight shows first evidence surface-induced ordering copolymers phase mixed state characterized by an...

The specular reflectivity of neutrons has been used to characterize quantitatively the microphase separated morphology symmetric, diblock copolymers polystyrene (PS), and polymethylmethacrylate (PMMA), as a function total molecular weight copolymer where either block is perdeuterated. It shown that hyperbolic tangent function, opposed linear or cosine-squared most closely describes concentration gradient at interface between lamellar microdomains. effective width found be independent blocks...

A microscopic magnetic antiphase domain structure has been observed in a single-crystal Gd-Y superlattice by neutron diffraction. Furthermore, this long-range antiferromagnetic correlation is found to occur multibilayer, which each bilayer consists of ${N}_{\mathrm{Gd}}$ ferromagnetic atomic planes Gd followed ${N}_{\mathrm{Y}}$ nonmagnetic Y, for ${N}_{\mathrm{Y}}={N}_{\mathrm{Gd}}=10$ but not ${N}_{\mathrm{Y}}=6 or 20$. This oscillatory behavior consistent with recent theoretical...

Polarized neutron reflectometry is used to probe the in-plane projection of net-magnetization vector $\stackrel{\ensuremath{\rightarrow}}{\mathrm{M}}$ polycrystalline Fe films exchange coupled twinned (110) $\mathrm{MnF}{}_{2}$ or $\mathrm{FeF}{}_{2}$ antiferromagnetic (AF) layers. The magnetization reversal mechanism depends upon orientation cooling field with respect microstructure AF, and whether applied increased (or decreased from) a positive saturating field; i.e., asymmetric. sample...

Specular reflection of neutrons has been used to characterize the structure single lipid bilayers adsorbed a planar silicon surface from aqueous solution. We novel experimental setup which significantly decreased incoherent background scattering and allowed us measure neutron reflectivities as low 5 × 10-7. Thicknesses length densities were determined by fitting procedure using (i) randomly generated smooth functions represented parametric B-splines (ii) stepped based on theoretical...

Neutron-scattering measurements have been performed to search for possible elastic incommensurate magnetic peaks in superconducting ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4}$ with $x=0.10,$ 0.12, and 0.15. The most dramatic effects are found $x=0.12;$ this case, the peak intensity first appears at onset of superconductivity ${T}_{c}(=31 \mathrm{K}).$ resolution-limited width indicates that static correlation length exceeds 200 \AA{} isotropically...

Abstract Advances in molecular beam epitaxy deposition techniques have recently made it possible to grow, an atomic plane at a time, single crystalline superlattices composed of alternating layers magnetic rare earth, such as Gd, Dy, Ho, or Er, and metallic Y, which has identical chemical structure. The primary goal this article is review the new interesting structures been discovered these novel superlattice systems consider what implications observed phases on our understanding underlying...

The ordering in thin films of symmetric diblock copolymers has been studied by neutron reflectivity as a function temperature and film thickness. Exponentially damped oscillatory variations the concentration are shown to propagate into specimens from both surfaces with decay lengths increasing decreasing temperature. No distinguishable order-to-disorder transition is observed; only partially fully ordered state found. this found depend power-law manner on

Polymer-based solar cell performance is dictated by nanoscale structures since the active layer suffers from extremely short exciton diffusion lengths. To understand structures' effect on we use neutron reflectivity to investigate thin film morphology containing a 1 : weight blend of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) nanoparticles and poly(3-hexylthiophene) (P3HT). Neutron uniquely suited this system due large scattering length density contrast between two components, other...

Neutron reflectometry measurements show that lamellar structures composed of thin alternating water-rich and Nafion-rich layers exist at the interface between SiO2 hydrated Nafion film. Lamellae thickness number increase with humidity. Some lamellae remain in film after dehydration. Multilayer are not observed for on Au or Pt surfaces. Instead, a partially single interfacial layer occurs decreases to few angstroms as humidity is reduced zero. The absorption isotherm rest similar bulk all...

Paramagnetic spin fluctuations in the weak itinerant-electron ferromagnet MnSi have been measured by using both unpolarized and polarized neutron scattering, scattering intensity was put on an absolute value simultaneous measurements of phonon cross sections. The magnetic excitation spectra over whole Brillouin zone, for a wide energy range from 0 to 20 meV (\ensuremath{\Elzxh}\ensuremath{\omega}/${\mathrm{kT}}_{c}$=7.9) up temperatures (T/${T}_{c}$=10) well above ${T}_{c}$, follow closely...

We present an experimental and theoretical investigation of the influence a uniaxial magnetocrystalline anisotropy on magnetic textures that are formed in chiral system. show epitaxially induced tensile stress MnSi thin films grown Si(111) creates easy-plane anisotropy. The magnetoelastic shear coefficient is derived from SQUID magnetometry measurements combination with transmission electron microscopy x-ray diffraction data. Density functional calculations support conclusion originates...

Through neutron diffraction experiments, including spin-polarized measurements, we find a collinear incommensurate spin-density wave with propagation vector $\mathbf{k}=$ [$0.4481(4)\phantom{\rule{0.16em}{0ex}}\phantom{\rule{0.16em}{0ex}}0\phantom{\rule{0.16em}{0ex}}\phantom{\rule{0.16em}{0ex}}\frac{1}{2}$] at base temperature in the superconducting parent compound Fe${}_{1+x}$Te. This critical concentration of interstitial iron corresponds to $x\ensuremath{\approx}12%$ and leads...

The magnetic and structural properties of molecular beam epitaxy grown Fe/Cr(001) superlattices were studied as a function the growth temperature ${\mathit{T}}_{\mathit{g}}$ using polarized neutron reflectometry (PNR) with polarization analysis, magneto-optic Kerr effect (MOKE), x-ray-scattering techniques. From MOKE PNR external field we find strong noncollinear coupling between Fe layers so far unexpected angle 50\ifmmode^\circ\else\textdegree\fi{} near remanence for sample at...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHomopolymer distributions in ordered block copolymersA. M. Mayes, T. P. Russell, S. K. Satija, and C. F. MajkrzakCite this: Macromolecules 1992, 25, 24, 6523–6531Publication Date (Print):November 1, 1992Publication History Published online1 May 2002Published inissue 1 November 1992https://pubs.acs.org/doi/10.1021/ma00050a022https://doi.org/10.1021/ma00050a022research-articleACS PublicationsRequest reuse permissionsArticle...

An elastic neutron scattering instrument, the advanced diffractometer/reflectometer (AND/R), has recently been commissioned at National Institute of Standards and Technology Center for Neutron Research. The AND/R is centerpiece Cold Neutrons Biology partnership, which dedicated to structural characterization thin films multilayers biological interest. instrument capable measuring both specular nonspecular reflectivity, as well crystalline or semicrystalline diffraction wave-vector transfers...

MnSi is a cubic ferromagnet with long-wavelength spiral below its Curie temperature at 29 K. Recent theoretical and experimental studies have shown that this only right handed because of the lack center symmetry in Mn atomic arrangement. We carried out elastic inelastic neutron scattering experiments on single crystal use polarized-beam technique. A characteristic polarization dependence was observed magnetic Bragg reflections phase, as well spin-wave excitations critical near ${T}_{c}$....

MnF(2)/Fe bilayers exhibit asymmetric magnetization reversal that occurs by coherent rotation on one side of the loop and nucleation propagation domain walls other loop. Here, we show polarized neutron reflectometry, magnetization, magnetotransport measurements for samples with good crystalline "quality" is a two-stage process, due to stable state perpendicular cooling field direction. The result remarkably asymmetrically shaped hysteresis loops.

Surface segregation in thin films of symmetric polyolefin diblock copolymers containing a lamellar microstructure, cast on variety substrates, has been investigated. In all cases, the conformationally smaller block preferentially segregated to both solid and air interfaces even though surface energy substrate always exceeded that copolymer. These results indicate an entropically driven effect we attribute conformational asymmetry.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTUnconventional morphologies of symmetric, diblock copolymers due to film thickness constraintsT. P. Russell, A. Menelle, S. H. Anastasiadis, K. Satija, and C. F. MajkrzakCite this: Macromolecules 1991, 24, 23, 6263–6269Publication Date (Print):November 1, 1991Publication History Published online1 May 2002Published inissue 1 November 1991https://pubs.acs.org/doi/10.1021/ma00023a032https://doi.org/10.1021/ma00023a032research-articleACS...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTWidth of homopolymer interfaces in the presence symmetric diblock copolymersT. P. Russell, A. Menelle, W. Hamilton, G. S. Smith, K. Satija, and C. F. MajkrzakCite this: Macromolecules 1991, 24, 20, 5721–5726Publication Date (Print):September 1, 1991Publication History Published online1 May 2002Published inissue 1 September 1991https://pubs.acs.org/doi/10.1021/ma00020a036https://doi.org/10.1021/ma00020a036research-articleACS PublicationsRequest...