Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Emergence of novel magnetic order at finite temperature in overdoped
  pnictides   We examine the temperature dependence of the magnetic ordering in the
frustrated Heisenberg $J_1-J_2$ model in presence of two different kind of
dopants: vacancies or magnetic impurities. We demonstrate that, irrespective to
their magnetic ratio, the introduction of impurities quenches the order by
disorder selection mechanism associated with an Ising-like phase transition at
low temperatures and gives way to a $90^\circ$ (anticollinear) order . The
presence of dopants triggers a non trivial competition between entropically
selected states (collinear) and energetically favoured ones (anticollinear) in
dependence of both dilution and temperature. While in case of magnetic
impurity, the interesting magnetic phases are observed for full range of
temperature and doping, in case of nonmagnetic impurities every magnetic order
is destroyed at all temperatures above $12\%$ dilution. At fixed low
temperature and tuning the doping we show a first order phase transition
leading to the re-entrance of the Ising-like order with percolation of islands
of $90^\circ$ order. At fixed doping and varying the temperature we observe a
transition from the anticollinear to the collinear phase assisted by a new
emerging magnetic phase in the presence of magnetic impurities, whilst in case
of vacancies this transition is characterised by a coexistent region of both.
Furthermore, tuning the magnetic moment of the impurities, a complete collapse
of the Ising-like order is attained. This is in agreement with observations of
Ir dopant atoms in superconducting Ba(Fe$_{1-x}$Ir$_x$)$_2$As$_2$ with
$x<0.047$.

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The categories of this paper are: acc-phys
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The categories of this paper are: atom-ph
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The categories of this paper are: solv-int
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The categories of this paper are: ao-sci
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The categories of this paper are: math-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: chem-ph
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The categories of this paper are: math
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The categories of this paper are: econ
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The categories of this paper are: hep-lat
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: funct-an