  In this study, novel use of the electromagnetic field profile of a localized
spoof surface plasmonic mode to detect electron spin resonance is being
reported. The mode is supported on a resonator with a complementary metallic
spiral structure, etched on the ground plane of a microstrip line having a
characteristic impedance of 50 $\Omega$. The change in characteristics of the
mode of interest with lowering of temperature has been observed and analyzed.
Electron spin resonance spectra of a standard paramagnetic sample,
2,2-diphenyl-1-picrylhydrazyl, are recorded using this resonator down to 10 K.
Potential application of the mode in the detection of microwave Rashba
field-driven electron spin resonance has been discussed.
