Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Growth of Ni and Ni-Cr Alloy Thin Films on MgO(001): Effect of Alloy
  Composition on Surface Morphology   The effects of substrate treatment, temperature and composition on the
surface morphology of Ni-Cr thin films grown on MgO(001) are studied by
scanning tunneling microscopy (STM) and atomic force microscopy (AFM). A
combination of acid-etching and high temperature deposition (400C) will result
in smooth films and terraces (up to 30 nm wide) suitable for the study of
progression of chemical reactions on the surface. Two different treatments are
used to prepare the MgO substrates for deposition and they introduce
characteristic differences in film surface morphology. Thin films that are
grown on the phosphoric acid-treated substrates present reduced nucleation
density during the initial stages of film growth which results in long and wide
terraces. Due to the about 16 percent lattice mismatch in the Ni(001)/MgO(001)
system, film growth at 400C yields discontinuous films and a two-step growth
process is necessary to obtain a continuous layer. Ni films are deposited at
100C and subjected to a post-growth anneal at 300C for 2 hours to obtain a
smoother surface. The addition of just 5 wt. percent Crchanges the growth
processes and yields continuous films at 400C without de-wetting in contrast to
pure Ni films. With increasing Cr content, the films become progressively
smoother with wider terraces. Ni5Cr alloy thin films have an rms surface
roughness of 3.63+/-0.75 nm while Ni33Cr thin film is smoother with an rms
roughness of only 0.29 +/-0.13 nm. The changes in film growth initiated by
alloying with Cr are due to changes in the interfacial chemistry which
favorably alters the initial adsorption of the metal atoms on MgO surface and
suggests a reduction of the Ehrlich-Schwoebel barrier. The growth of smooth
Ni-Cr thin films with well-defined surface structure opens up a new pathway for
a wide range of surface science studies related to alloy performance.

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The categories of this paper are: hep-ph
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The categories of this paper are: math-ph
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The categories of this paper are: gr-qc
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
31
The categories of this paper are: ao-sci
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
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The categories of this paper are: stat
28
The categories of this paper are: alg-geom
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-lat
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The categories of this paper are: atom-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: mtrl-th