Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Understanding ferromagnetism in Cr-based 3d-5d double perovskites   Ferromagnetism in Cr-based double perovskites is analyzed using effective
model as well as simulation approach.
  Starting from a microscopic model proposed recently for this class of double
perovskites, an effective spin-only model is derived in the limit of large
exchange coupling at the B-site. Analytic expressions for the resultant
exchange coupling is derived in certain limiting cases.
  The behaviour of this exchange is used to provide a plausible explanation for
the enhanced ferromagnetic tendency as also the enigmatic increase in Curie
temperature observed in Cr-based DP-s, in the series
Sr$_{2}$CrWO$_{6}$,Sr$_{2}$CrReO$_{6}$ to Sr$_{2}$CrOsO$_{6}$. The
superexchange between neighbouring B and B' sites is found to play a crucial
role both in stabilizing ferromagnetism, especially in the latter two
compounds, as well as increasing the T$_{c}$.

15
The categories of this paper are: nucl-ex
27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol
31
The categories of this paper are: ao-sci
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
21
The categories of this paper are: adap-org
16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
17
The categories of this paper are: q-fin
3
The categories of this paper are: physics
37
The categories of this paper are: supr-con
1
The categories of this paper are: cs
2
The categories of this paper are: math