Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Lattice collapse and the magnetic phase diagram of
  Sr$_{1-x}$Ca$_x$Co$_2$P$_2$   We report that the 122 type Sr$_{1-x}$Ca$_x$Co$_2$P$_2$ solid solution
undergoes an anomalous structural transition from the uncollapsed to the
collapsed ThCr$_2$Si$_2$ structure at a distinct onset composition near
$x=0.5$. Correlated with the structural changes, the electronic system evolves
from a nearly ferromagnetic Fermi liquid to an antiferromagnetic metal, through
a complex crossover regime. The structural collapse, driven by P-P bonding
across the (Sr,Ca) layers, is much more pronounced in this system than it is in
the analogous Fe-based system, indicating a strong sensitivity of structure to
total electron count in the transition metal pnictide 122 family.

6
The categories of this paper are: astro-ph
21
The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
17
The categories of this paper are: q-fin
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
8
The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
25
The categories of this paper are: patt-sol
19
The categories of this paper are: eess
37
The categories of this paper are: supr-con
33
The categories of this paper are: plasm-ph