Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetic and thermodynamic properties of Cu$_x$TiSe$_2$ single crystals   We present a detailed study of the phase diagram of copper intercalated
TiSe$_2$ single crystals, combining local Hall-probe magnetometry, tunnel diode
oscillator technique (TDO), specific-heat, and angle-resolved photoemission
spectroscopy measurements. A series of the Cu$_x$TiSe$_2$ samples from three
different sources with various copper content $x$ and superconducting critical
temperatures $T_c$ have been investigated. We first show that the vortex
penetration mechanism is dominated by geometrical barriers enabling a precise
determination of the lower critical field, $H_{c1}$. We then show that the
temperature dependence of the superfluid density deduced from magnetic
measurements (both $H_{c1}$ and TDO techniques) clearly suggests the existence
of a small energy gap in the system, with a coupling strength $2\Delta_s \sim
[2.4-2.8]k_BT_c$, regardless of the copper content, in puzzling contradiction
with specific heat measurements which can be well described by one single large
gap $2\Delta_l \sim [3.7-3.9]k_BT_c$. Finally, our measurements reveal a
non-trivial doping dependence of the condensation energy, which remains to be
understood.

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The categories of this paper are: cs
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The categories of this paper are: math
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The categories of this paper are: physics
26
The categories of this paper are: bayes-an
29
The categories of this paper are: funct-an
14
The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
6
The categories of this paper are: astro-ph
30
The categories of this paper are: q-alg
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The categories of this paper are: mtrl-th
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The categories of this paper are: solv-int
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The categories of this paper are: plasm-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: nlin
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The categories of this paper are: nucl-ex