Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Thermodynamic signature of a magnetic-field-driven phase transition
  within the superconducting state of an underdoped high-temperature
  superconductor   More than a quarter century after the discovery of the high temperature
superconductor (HTS) YBa$_2$Cu$_3$O$_{6+\delta}$ (YBCO) studies continue to
uncover complexity in its phase diagram. In addition to HTS and the pseudogap
there is growing evidence for multiple phases with boundaries which are
functions of temperature ($T$), doping (p) and magnetic field. Here we report
the low temperature electronic specific heat (C$_{elec}$) of YBCO6.47 (p=0.08)
up to a magnetic field (H) of 34.5 teslas (T), a poorly understood region of
the underdoped H-$T$-p phase space. We observe two regimes: below a
characteristic magnetic field H'$\approx$10 T, C$_{elec}/T$ obeys an expected
H$^{1/2}$ behavior, however, near H' there is a sharp inflection followed by a
linear-in-H behavior. H' rests deep within the superconducting phase and the
linear-in-H behavior is observed in the zero resistance regime. In the limit of
zero temperature, C$_{elec}/T$ is proportional to the zero-energy electronic
density of states. Thus this inflection is evidence of a magnetic-field-driven
quantum phase transition.

21
The categories of this paper are: adap-org
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
6
The categories of this paper are: astro-ph
19
The categories of this paper are: eess
20
The categories of this paper are: acc-phys
22
The categories of this paper are: chao-dyn
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
32
The categories of this paper are: atom-ph
13
The categories of this paper are: quant-ph
37
The categories of this paper are: supr-con
2
The categories of this paper are: math
15
The categories of this paper are: nucl-ex
33
The categories of this paper are: plasm-ph