  DNA has a well-defined structural transition -- the denaturation of its
double-stranded form into two single strands -- that strongly affects its
thermal transport properties. We show that, according to a widely implemented
model for DNA denaturation, one can engineer DNA "heattronic" devices that have
a rapidly increasing thermal conductance over a narrow temperature range across
the denaturation transition (~350 K). The origin of this rapid increase of
conductance, or "switching", is the softening of the lattice and suppression of
nonlinear effects as the temperature crosses the transition temperature and DNA
denatures. Most importantly, we demonstrate that DNA nanojunctions have a broad
range of thermal tunability due to varying the sequence and length, and
exploiting the underlying nonlinear behavior. We discuss the role of disorder
in the base sequence, as well as the relation to genomic DNA. These results set
the basis for developing thermal devices out of materials with nonlinear
structural dynamics, as well as understanding the underlying mechanisms of DNA
denaturation.
