Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Field-dependent spin and heat conductivities of dimerized spin-1/2
  chains   We study the spin and heat conductivity of dimerized spin-1/2 chains in
homogeneous magnetic fields at finite temperatures. At zero temperature, the
model undergoes two field-induced quantum phase transitions from a dimerized,
into a Luttinger, and finally into a fully polarized phase. We search for
signatures of these transitions in the spin and heat conductivities. Using
exact diagonalization, we calculate the Drude weights, the frequency dependence
of the conductivities, and the corresponding integrated spectral weights. As a
main result, we demonstrate that both the spin and heat conductivity are
enhanced in the gapless phase and most notably at low frequencies. In the case
of the thermal conductivity, however, the field-induced increase seen in the
bare transport coefficients is suppressed by magnetothermal effects, caused by
the coupling of the heat and spin current in finite magnetic fields. Our
results complement recent magnetic transport experiments on spin ladder
materials with sufficiently small exchange couplings allowing access to the
field-induced transitions.

11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
2
The categories of this paper are: math
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
27
The categories of this paper are: comp-gas
14
The categories of this paper are: math-ph
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
28
The categories of this paper are: alg-geom
22
The categories of this paper are: chao-dyn
12
The categories of this paper are: nucl-th
7
The categories of this paper are: hep-th
9
The categories of this paper are: nlin