In disk drive technology, lubricant thickness and roughness are important, but often overlooked, contributors to slider–disk spacing. In this paper, we use X-ray reflectivity to measure the thickness and lubricant–air roughness of a perfluoropolyether lubricant (Fomblin Zdol) on silicon wafers and carbon overcoats. For Zdol on smooth silicon, the roughness increases with increasing lubricant th...

The question of how bulk electronic order is terminated at a surface is an intriguing one, and one with possible practical implications--for example in nanoscaled systems that may be characterized by their surface behaviour. One example of such order is orbital order, and in principle it should be possible to probe the termination of this order with surface X-ray scattering. Here, we report the...

Spin-echo small-angle neutron scattering is able to characterize powders in terms of their density-density correlation function. Here we present a microstructural study on a fine cohesive powder undergoing uniaxial compression. As a function of compression, we measure the autocorrelation function of the density distribution. From these measurements we quantify the typical sizes of the heterogen...

As every driver knows, when pavement deteriorates, it becomes rougher. What drivers may not realize is that the roughness they feel in the seat of their vehicles not only makes the drive less comfortable, but it also leads to a cycle of increasing deterioration rates with increasing roughness severity. To prevent this cycle of everincreasing roughness and deter iorat ion, engineers try to perfo...

Learning curves for Gaussian process regression are well understood when the 'student' model happens to match the 'teacher' (true data generation process). I derive approximations to the learning curves for the more generic case of mismatched models, and find very rich behaviour: For large input space dimensionality, where the results become exact, there are universal (student-independent) plat...

The lamellar D spacing has been measured for oriented stacks of lecithin bilayers prepared on a variety of solid substrates and hydrated from the vapor. We find that, when the bilayers are in the L(alpha) phase near 100% relative humidity, the D spacing is consistently larger when the substrate is rougher than when it is smooth. The differences become smaller as the relative humidity is decreas...

Multigrid methods are analyzed in the style of standard iterative methods. A basic error bound is derived in terms of residuals on neighboring levels. The terms in this bound derive from the iterative methods used as smoothers on each level and the operators used to go from a level to the next coarser level. This bound is correct whether the underlying operator is symmetric or nonsymmetric, de ...

The evolution of nanostructure morphology and local chemical environment during heteoepitaxial growth of aluminum selenide on Si(111) was investigated with scanning tunneling microscopy and high resolution photoemission spectroscopy. Despite the strong similarity to GaSe in atomic and electronic structure during deposition of the first AlSe bilayer, subsequent growth is quite different, resulti...

Microscopy and diffraction measurements are presented of ultrathin binary alloy films ruthenium molybdenum that obtained by standard sputter deposition . For compositions close to Ru 50 Mo , we find the be amorphous. The amorphicity is accompanied a significant reduction roughness with respect equally thick either or molybdenum. We ascribe this absence grain structure characteristic polycrystal...

The effect of surface roughness on the structure of liquid crystalline fluids near solid substrates is studied by Monte Carlo simulations. The liquid crystal is modeled as a fluid of soft ellipsoidal molecules and the substrate is modeled as a hard wall that excludes the centers of mass of the fluid molecules. Surface roughness is introduced by embedding a number of molecules with random positi...