Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Kinetic Roughening of Ion-Sputtered Pd(001) Surface: Beyond the
  Kuramoto-Sivashinsky Model   We investigate the kinetic roughening of Ar$^+$ ion-sputtered Pd(001) surface
both experimentally and theoretically. \textit{In situ} real-time x-ray
reflectivity and \textit{in situ} scanning tunneling microscopy show that
nanoscale adatom islands form and grow with increasing sputter time $t$.
Surface roughness, $W(t)$, and lateral correlation length, $\xi(t)$, follows
the scaling laws, $W(t)\sim t^{\beta}$ and $\xi(t)\sim t^{1/z}$ with the
exponents $\beta\simeq 0.20$ and $1/z\simeq 0.20$, for ion beam energy
$\epsilon=0.5$ keV, which is inconsistent with the prediction of the
Kuramoto-Sivashinsky (KS) model. We thereby extend the KS model by applying the
Sigmund theory of sputter erosion to the higher order, ${\cal O}(\nabla^4,
h^2)$, where $h$ is surface height, and derive a new term of the form
$\nabla^2(\nabla h)^2$ which plays an indispensable role in describing the
observed morphological evolution of the sputtered surface.

15
The categories of this paper are: nucl-ex
13
The categories of this paper are: quant-ph
5
The categories of this paper are: gr-qc
22
The categories of this paper are: chao-dyn
20
The categories of this paper are: acc-phys
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
16
The categories of this paper are: stat
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
25
The categories of this paper are: patt-sol
23
The categories of this paper are: solv-int
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The categories of this paper are: hep-lat
9
The categories of this paper are: nlin
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph