Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: High and low-temperature crystal and magnetic structures of
  epsilon-Fe2O3 and their correlation to its magnetic properties   The crystal and magnetic structures of the orthorhombic e-Fe2O3 have been
studied by simultaneous Rietveld refinement of X-ray and neutron powder
diffraction data in combination with Mossbauer spectroscopy, as well as
magnetisation and heat capacity measurements. It has been found that above 150
K the e-Fe2O3 polymorph is a collinear ferrimagnet with the magnetic moments
directed along the a axis, while the magnetic ordering below 80 K is
characterised by a square-wave incommensurate structure. The transformation
between these two states is a second order phase transition and involves subtle
structural changes mostly affecting the coordination of the tetrahedral and one
of the octahedral Fe sites. The temperature dependence of the e-Fe2O3 magnetic
properties is discussed in the light of these results.

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The categories of this paper are: hep-ph
19
The categories of this paper are: eess
29
The categories of this paper are: funct-an
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
3
The categories of this paper are: physics
11
The categories of this paper are: hep-lat
9
The categories of this paper are: nlin
27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
17
The categories of this paper are: q-fin
28
The categories of this paper are: alg-geom
24
The categories of this paper are: dg-ga