Microresonator for the EPR experiments

R. Narkowicz

Outline

Concept of the microresonatorExperimental and technoligical constraintsMicrocoil design and optimization Experimental verification of the designNext stepsConclusions

Concept of the microresonator

Sensitivity of the resonator for small samples can be increased by minimizing its size and thus increasing the filling factor Resonator built with discrete components has to be at least order of magnitude smaller than the operation wavelengthExperience with such a resonators in a field of NMR confirms that sensitivity varies inver-sely with linear dimensions of the elements

Planar elements are ideal to be manu-factured by means of standard micro-technologyPlanar microcoil is well suited for the mono-layers of of N@C60 and can be desig-ned on the same Si substrate, on which fullerenes can be depositedSi substrate would provide the heat sink required for the operation at high current densities in small size elements

Technological constraints

Microcoil design and optimization

main optimization criterion– signal-to-noise ratiosignal can be maximized byincreasing magnetic fieldnoise can be reduced by minimizing trace resistance

optimization results

R

IBNS 1~)/(

3D electrodynamic simulation – surface current

3D electrodynamic simulation – magnetic field distribution

Tuning the microcoil with the shunt stub

CW EPR of DPPH f=14GHz

490 495 500 505 510

U E

PR,

arb

.u.

B, mT

spectrometer sensitivity

B-Field / mT

ODMR of a single N-V defectin diamond

WmT

TB

R

2.12

41

Next steps

Smaller coilsNumerical modeling of skin- and proximity effects New substrates with lower losses (glass) or better thermal conductivity (Si)Coplanar waveguide as an alternative coupling system

Conclusions

The sensitivity of the microcoil prototype is comparable with that of conventional cavity The further miniaturization of the microcoil should made it superior to the waveguide cavity for the samples containing small number of spins