Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetic properties of BaCdVO(PO_4)_2: a strongly frustrated spin-1/2
  square lattice close to the quantum critical regime   We report magnetization and specific heat measurements on polycrystalline
samples of BaCdVO(PO_4)_2 and show that this compound is a S=1/2 frustrated
square lattice with ferromagnetic nearest-neighbor (J_1) and antiferromagnetic
next-nearest-neighbor (J_2) interactions. The coupling constants J_1\simeq -3.6
K and J_2\simeq 3.2 K are determined from a fitting of the susceptibility data
and confirmed by an analysis of the saturation field (H_s=4.2 T), the specific
heat, and the magnetic entropy. BaCdVO(PO_4)_2 undergoes magnetic ordering at
about 1 K, likely towards a columnar antiferromagnetic state. We find that
BaCdVO(PO_4)_2 with the frustration ratio \alpha=J_2/J_1\simeq -0.9 is closer
to a critical (quantum spin liquid) region of the frustrated square lattice
than any of the previously reported compounds. Positive curvature of the
magnetization curve is observed in agreement with recent theoretical
predictions for high-field properties of the frustrated square lattice close to
the critical regime.

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The categories of this paper are: gr-qc
32
The categories of this paper are: atom-ph
33
The categories of this paper are: plasm-ph
37
The categories of this paper are: supr-con
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The categories of this paper are: acc-phys
24
The categories of this paper are: dg-ga
31
The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas
13
The categories of this paper are: quant-ph
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The categories of this paper are: hep-th
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The categories of this paper are: eess
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The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
28
The categories of this paper are: alg-geom
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-ex