Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Origin and tuning of the magnetocaloric effect for the magnetic
  refrigerant MnFe(P1-xGex)   Neutron diffraction and magnetization measurements of the magneto refrigerant
Mn1+yFe1-yP1-xGex reveal that the ferromagnetic and paramagnetic phases
correspond to two very distinct crystal structures, with the magnetic entropy
change as a function of magnetic field or temperature being directly controlled
by the phase fraction of this first-order transition. By tuning the physical
properties of this system we have achieved a maximum magnetic entropy change
exceeding 74 J/Kg K for both increasing and decreasing field, more than twice
the value of the previous record.

13
The categories of this paper are: quant-ph
23
The categories of this paper are: solv-int
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
14
The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg
20
The categories of this paper are: acc-phys
34
The categories of this paper are: chem-ph
24
The categories of this paper are: dg-ga
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
2
The categories of this paper are: math
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
3
The categories of this paper are: physics
37
The categories of this paper are: supr-con