Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Thermodynamic Properties of the Spin-1/2 Antiferromagnetic ladder
  Cu2(C2H12N2)2Cl4 under Magnetic Field   Specific heat ($C_V$) measurements in the spin-1/2
Cu$_2$(C$_2$H$_{12}$N$_2$)$_2$Cl$_4$ system under a magnetic field up to
$H=8.25 T$ are reported and compared to the results of numerical calculations
based on the 2-leg antiferromagnetic Heisenberg ladder. While the temperature
dependences of both the susceptibility and the low field specific heat are
accurately reproduced by this model, deviations are observed below the critical
field $H_{C1}$ at which the spin gap closes. In this Quantum High Field phase,
the contribution of the low-energy quantum fluctuations are stronger than in
the Heisenberg ladder model. We argue that this enhancement can be attributed
to dynamical lattice fluctuations. Finally, we show that such a Heisenberg
ladder, for $H>H_{C1}$, is unstable, when coupled to the 3D lattice, against a
lattice distortion. These results provide an alternative explanation for the
observed low temperature ($T_C\sim 0.5K$ -- $0.8K$) phase (previously
interpreted as a 3D magnetic ordering) as a new type of incommensurate gapped
state.

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The categories of this paper are: cmp-lg
13
The categories of this paper are: quant-ph
21
The categories of this paper are: adap-org
2
The categories of this paper are: math
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
20
The categories of this paper are: acc-phys
5
The categories of this paper are: gr-qc
22
The categories of this paper are: chao-dyn
8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph
1
The categories of this paper are: cs
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The categories of this paper are: eess
16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
26
The categories of this paper are: bayes-an