Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evolution of two bulk-superconducting phases in Sr0.5RE0.5FBiS2 (RE: La,
  Ce, Pr, Nd, Sm) by external hydrostatic pressure effect   Polycrystalline samples of Sr1-xRExFBiS2 (RE: La, Ce, Pr, Nd, and Sm) were
synthesized via the solid-state reaction and characterized using synchrotron
X-ray diffraction. Although all the Sr0.5RE0.5FBiS2 samples exhibited
superconductivity at transition temperatures (Tc) within the range of 2.1-2.7 K
under ambient pressure, the estimated superconducting volume fraction was
small. This indicated the non-bulk nature of superconductivity in these samples
under ambient pressure. A dramatic evolution of the bulk superconducting phases
was achieved on applying an external hydrostatic pressure. Near pressures below
1 GPa, bulk superconductivity was induced with a Tc of 2.5-2.8 K, which is
termed as the low-P phase. Moreover, the high-P phase (Tc = 10.0-10.8 K)
featuring bulk characteristics was observed at higher pressures. Pressure-Tc
phase diagrams indicated that the critical pressure for the emergence of the
high-P phase tends to increase with decreasing ionic radius of the doped RE
ions. According to the high-pressure X-ray diffraction measurements of
Sr0.5La0.5FBiS2, a structural phase transition from tetragonal to monoclinic
also occurred at approximately 1.1 GPa. Thus, this phase transition indicates a
pressure-induced superconducting-superconducting transition similar to the
transition in LaO0.5F0.5BiS2. Bulk superconducting phases in Sr0.5RE0.5FBiS2
induced by the external hydrostatic pressure effect are expected to be useful
for evaluating the mechanisms of superconductivity in BiCh2-based
superconductors.

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The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg
3
The categories of this paper are: physics
19
The categories of this paper are: eess
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The categories of this paper are: q-fin
33
The categories of this paper are: plasm-ph
29
The categories of this paper are: funct-an
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th
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The categories of this paper are: alg-geom
32
The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
24
The categories of this paper are: dg-ga
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The categories of this paper are: econ
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The categories of this paper are: solv-int