Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Frustrated ferromagnetic spin-1/2 chain in a magnetic field: The phase
  diagram and thermodynamic properties   The frustrated ferromagnetic spin-1/2 Heisenberg chain is studied by means of
a low-energy field theory as well as the density-matrix renormalization group
and exact diagonalization methods. Firstly, we study the ground-state phase
diagram in a magnetic field and find an `even-odd' (EO) phase characterized by
bound pairs of magnons in the region of two weakly coupled antiferromagnetic
chains. A jump in the magnetization curves signals a first-order transition at
the boundary of the EO phase, but otherwise the curves are smooth. Secondly, we
discuss thermodynamic properties at zero field, where we confirm a double-peak
structure in the specific heat for moderate frustrating next-nearest neighbor
interactions.

11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con
8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg
13
The categories of this paper are: quant-ph
14
The categories of this paper are: math-ph
35
The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th
6
The categories of this paper are: astro-ph
19
The categories of this paper are: eess
7
The categories of this paper are: hep-th