Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Phase transitions in nanosystems caused by interface motion: The Ising
  bi-pyramid with competing surface fields   The phase behavior of a large but finite Ising ferromagnet in the presence of
competing surface magnetic fields +/- H_s is studied by Monte Carlo simulations
and by phenomenological theory. Specifically, the geometry of a double pyramid
of height 2L is considered, such that the surface field is positive on the four
upper triangular surfaces of the bi-pyramid and negative on the lower ones. It
is shown that the total spontaneous magnetization vanishes (for L -> infinity)
at the temperature T_f(H), related to the "filling transition" of a
semi-infinite pyramid, which can be well below the critical temperature of the
bulk. The discontinuous vanishing of the magnetization is accompanied by a
susceptibility that diverges with a Curie-Weiss power law, when the transition
is approached from either side. A Landau theory with size-dependent critical
amplitudes is proposed to explain these observations, and confirmed by finite
size scaling analysis of the simulation results. The extension of these results
to other nanosystems (gas-liquid systems, binary mixtures, etc.) is briefly
discussed.

10
The categories of this paper are: q-bio
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
26
The categories of this paper are: bayes-an
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph
21
The categories of this paper are: adap-org
37
The categories of this paper are: supr-con
2
The categories of this paper are: math
11
The categories of this paper are: hep-lat
24
The categories of this paper are: dg-ga
8
The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex