  We demonstrate a novel method based on the Zeeman splitting of electronic
spins to improve the performance for temperature sensing of negatively-charged
nitrogen-vacancy (NV) centers in multiple-poly diamond. The theoretical model
for selection principle of resonance peaks corresponding to a single NV axis
for determining the temperature dependence is clarified. The spectral linewidth
is effectively narrowed and the thermometer is insensitive to magnetic field
fluctuations. Repeatability and accuracy of the relationship calibration
between the zero-field splitting (ZFS) parameter D and temperature T in the
range of 298 K to 323 K is significantly improved, and the results of
coefficient dD/dT is 75.33 kHz/K. Finally, this method promotes the average
temperature measurement sensitivity (below 10 Hz) of our setup from 0.49
K/Hz1/2 to 0.22 K/Hz1/2.
