Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Integral and fractional Quantum Hall Ising ferromagnets   We compare quantum Hall systems at filling factor 2 to those at filling
factors 2/3 and 2/5, corresponding to the exact filling of two lowest electron
or composite fermion (CF) Landau levels. The two fractional states are examples
of CF liquids with spin dynamics. There is a close analogy between the
ferromagnetic (spin polarization P=1) and paramagnetic (P=0) incompressible
ground states that occur in all three systems in the limits of large and small
Zeeman spin splitting. However, the excitation spectra are different. At
filling factor 2, we find spin domains at half-polarization (P=1/2), while
antiferromagnetic order seems most favorable in the CF systems. The transition
between P=0 and 1, as seen when e.g. the magnetic field is tilted, is also
studied by exact diagonalization in toroidal and spherical geometries. The
essential role of an effective CF-CF interaction is discussed, and the
experimentally observed incompresible half-polarized state is found in some
models.

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The categories of this paper are: patt-sol
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The categories of this paper are: q-bio
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The categories of this paper are: econ
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The categories of this paper are: math-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: alg-geom
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The categories of this paper are: astro-ph
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The categories of this paper are: stat
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The categories of this paper are: plasm-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: solv-int
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The categories of this paper are: mtrl-th
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The categories of this paper are: adap-org
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The categories of this paper are: q-fin
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The categories of this paper are: math