Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetization of underdoped YBa$_2$Cu$_3$O$_{y}$ above the
  irreversibility field   Torque magnetization measurements on YBa$_2$Cu$_3$O$_{y}$ (YBCO) at doping
$y=6.67$($p=0.12$), in DC fields ($B$) up to 33 T and temperatures down to 4.5
K, show that weak diamagnetism persists above the extrapolated irreversibility
field $H_{\rm irr} (T=0) \approx 24$ T. The differential susceptibility
$dM/dB$, however, is more rapidly suppressed for $B\gtrsim 16$ T than expected
from the properties of the low field superconducting state, and saturates at a
low value for fields $B \gtrsim 24$ T. In addition, torque measurements on a
$p=0.11$ YBCO crystal in pulsed field up to 65 T and temperatures down to 8 K
show similar behaviour, with no additional features at higher fields. We
discuss several candidate scenarios to explain these observations: (a)
superconductivity survives but is heavily suppressed at high field by
competition with CDW order; (b) static superconductivity disappears near 24 T
and is followed by a region of fluctuating superconductivity, which causes
$dM/dB$ to saturate at high field; (c) the stronger 3D ordered CDW that sets in
above 15 T may suppress the normal state spin susceptibility sufficiently to
give an apparent diamagnetism of the magnitude observed.

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The categories of this paper are: adap-org
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The categories of this paper are: chao-dyn
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The categories of this paper are: math
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The categories of this paper are: astro-ph
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The categories of this paper are: math-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: mtrl-th
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The categories of this paper are: cs
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The categories of this paper are: q-bio
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The categories of this paper are: dg-ga
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The categories of this paper are: supr-con
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The categories of this paper are: atom-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: bayes-an