Amorphous thin film growth: theory compared with experiment

Experimental results on amorphous ZrAlCu thin film growth and the dynamics of the surface morphology as predicted from a minimal nonlinear stochastic deposition equation are analysed and compared. Key points of this study are (i) an estimation procedure for coefficients entering into the growth equation and (ii) a detailed analysis and interpretation of the time evolution of the correlation length and the surface roughness. The results corroborate the usefulness of the deposition equation as a tool for studying amorphous growth processes.Comment: 7 pages including 5 figure

Anelastic relaxation behavior and thermal stability of undercooled metallic melts in the amorphous Zr65AlxCu35-x system

Anelastic relaxation behavior and thermal stability of undercooled metallic melts in the amorphous Zr65AlxCu35-x system / M. Weiss, M. Moske and K. Samwer. - In: Physical review. B. 58. 1998. S. 9062-906

Early stages in amorphous

Ultra thin ${\rm Zr_{65}Al_{7.5}Cu_{27.5}}$ metallic glass films, deposited by electron beam evaporation onto HOPG (Highly Oriented Pyrolytic Graphite), are investigated in situ with STM with regard to the beginning of amorphous film growth and to atomic structures visible by STM. Island growth with coalescence at 5.0 nm film thickness is observed, where surface diffusion is discussed to be a dominating mechanism in forming the morphology by the use of a statistical analysis. On top of the islands additional structures on an atomic scale can be resolved

Thermal expansion of amorphous Zr

The thermal expansion of non-crystalline Zr65Al7.5Cu17.5 Ni10 has been studied in the range of the glass transition and in the undercooled liquid using a dilatometric device. The measuring technique used permits reliable experimental results up to 40 K above the glass transition temperature. The linear thermal expansion coefficient obtained is almost constant in the glassy state with a value of $8.0 \times 10^{-6} \rm K^{-1}$. It discontinuously increases at the glass transition temperature yielding a value of $20.0 \times 10^{-6} \rm K^{-1}$ in the undercooled liquid. The results are compared with specific heat measurements of the amorphous material in this temperature range and are interpreted in the framework of a cluster model

Interlayer coupling and magnetoresistance in Ir/Co multilayers

Fcc(111) oriented Ir/Co multilayers were prepared to study their magnetic and magnetotransport properties. The superlattice structure was characterized by X-ray diffraction. Results measured for magnetization and magnetoresistance ($\Delta R/R$) exhibit an oscillatory interlayer exchange coupling with a period of about $1\;$nm (4.5 monolayers). The coupling strength JAF and the largest $\Delta R/R$ obtained are $\rm -2.05\;mJ/m^2$ and 4% (at 10 K), respectively. The observed oscillatory behavior can be attributed to an interaction of separated Co magnetic layers, which must be some sort of RKKY coupling. Using this concept, we find a match of the measured oscillation period with the relevant wave vector on the Fermi surfaces of Ir

Specific heat of Zr

Dynamic calorimetric measurements are performed for the quaternary metallic glass Zr65Al7.5Cu17.5Ni10 in order to analyse the dependence on different heating rates for the glass transition temperature Tg. We compare two different temperature programs used for sample relaxation, to estimate the influence of the thermal history on Tg. A lower limit for the glass transition temperature Tg was calculated according to two different models based on the fact, that width and temperature of the glass transition depend on the experimental time scale set by the heating rate: One model assumes a Vogel-Fulcher-Tammann type behaviour, as used to describe more or less "fragile" glass formers and the other assumes an Arrhenius-like behaviour, which is related to "strong" glass formers. The values obtained from both models differ by about 80K. From additional absolute specific heat capacity measurements we calculate the Kauzmann temperature TK, as a lower limit for the temperature of the glass transition from thermodynamic aspects. Comparing TK with the temperature values obtained from the two evaluation models we can classify the quaternary metallic glass Zr65Al7.5Cu17.5Ni10, to behave more like a "strong" glass former

Oscillations of giant magnetoresistance in Cu/AgCo granular multilayers

A novel granular multilayer structure consisting of magnetic granular AgCo layers and non-magnetic Cu spacer layers is introduced to study their magnetotransport properties. The results are similar to those obtained from both conventional multilayers and granular single-films, but with a notable enhancement of low-field sensitivity compared to these structures. This can be attributed to a weak antiferromagnetic coupling across the Cu spacer layer between interfacial Co particles. Direct evidence for this interlayer coupling is given by the observation of magnetoresistance oscillations with variation of the Cu spacer thickness. The oscillation period obtained here for Cu(111) spacer layers is close to 3 atomic layers

Amorphous thin-film growth: Theory compared with experiment

Experimental results on amorphous ZrAlCu thin-film growth and the dynamics of the surface morphology as predicted from a minimal nonlinear stochastic deposition equation are analysed and compared. Key points of this study are: i) an estimation procedure for coefficients entering into the growth equation and ii) a detailed analysis and interpretation of the time evolution of the correlation length and the surface roughness. The results corroborate the usefulness of the deposition equation as a tool for studying amorphous growth processes

Determination of the Height-Height Correlation Function of Rough Surfaces from Diffuse X-Ray Scattering

We show that the height-height correlation function of a rough surface can be determined from the diffuse x-ray scattering intensity by an explicit back-transformation without any model assumptions. This is in contrast to the conventional fitting procedure of the data with parameterized correlation functions. The method is illustrated by the example of an amorphous Zr35Co65 film evaporated on a silicon substrate with native oxide. The height-height correlation function obtained from the diffuse-scattering data is compared to the result of in situ STM measurements