  In recent decades, there has been a persistent pursuit of applications for
surface/edge states in topological systems, driven by their dissipationless
transport effects. However, there have been limited tangible breakthroughs in
this field. This work demonstrates the remarkable properties of the topological
insulator Ta2Pd3Te5, as a thermometer. This material exhibits a power-law
correlation in temperature-dependent resistance at low temperatures, stemming
from its Luttinger liquid behavior of edge states, while exhibiting
semiconductor behavior at high temperatures. The power-law behavior effectively
addresses the issue of infinite resistance in semiconductor thermometers at
ultra-low temperatures, thereby playing a crucial role in enabling efficient
thermometry in refrigerators supporting millikelvin temperatures or below. By
employing chemical doping, adjusting thickness, and controlling gate voltage,
its power-law behavior and semiconductor behavior can be effectively modulated.
This enables efficient thermometry spanning from millikelvin temperatures to
room temperature, and allows for precise local temperature measurement.
Furthermore, this thermometer exhibits excellent temperature sensitivity and
resolution, and can be fine-tuned to show small magnetoresistance. In summary,
the Ta2Pd3Te5 thermometer, also referred to as a topological thermometer,
exhibits outstanding performance and significant potential for measuring a
wider range of temperatures compared to conventional low-temperature
thermometers.
