  The macroscopic control of ubiquitous heat flow remains poorly explored due
to the lack of a fundamental theoretical method. Here, by establishing
temperature-dependent transformation thermotics for treating materials whose
conductivity depends on temperature, we show analytical and simulation evidence
for switchable thermal cloaking and a macroscopic thermal diode based on the
cloaking. The latter allows heat flow in one direction but prohibits the flow
in the opposite direction, which is also confirmed by our experiments. Our
results suggest that the temperature-dependent transformation thermotics could
be a fundamental theoretical method for achieving macroscopic heat
rectification, and provide guidance both for macroscopic control of heat flow
and for the design of the counterparts of switchable thermal cloaks or
macroscopic thermal diodes in other fields like seismology, acoustics,
electromagnetics, or matter waves.

Materials Science