Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetic phases of the mixed-spin $J_1-J_2$ Heisenberg model on a square
  lattice   We study the zero-temperature phase diagram and the low-energy excitations of
a mixed-spin ($S_1>S_2$) $J_1-J_2$ Heisenberg model defined on a square lattice
by using a spin-wave analysis, the coupled cluster method, and the Lanczos
exact-diagonalization technique. As a function of the frustration parameter
$J_2/J_1$ ($ >0$), the phase diagram exhibits a quantized ferrimagnetic phase,
a canted spin phase, and a mixed-spin collinear phase. The presented results
point towards a strong disordering effect of the frustration and quantum spin
fluctuations in the vicinity of the classical spin-flop transition. In the
extreme quantum system $(S_1,S_2)=(1,{1/2})$, we find indications of a new
quantum spin state in the region $0.46< J_2/J_1<0.5$

27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math
5
The categories of this paper are: gr-qc
17
The categories of this paper are: q-fin
8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph
23
The categories of this paper are: solv-int
36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th
32
The categories of this paper are: atom-ph
15
The categories of this paper are: nucl-ex
14
The categories of this paper are: math-ph