Application of organic and copper-oxide superconductors for EPR imaging

A new electron paramagnetic resonance (EPR) imaging method on the surface of a super-conducting finite-size plate is experimentally demonstrated. The single crystals of the layered organic charge-transfer saltk-(ET)2Cu(NCS)2 and copper oxide YBa2Cu3O6.95 are applied to create field gradients up to 0.5 and 5 kG/cm respectively. Surface gradient mapping at different temperatures and de field excursions is carried out. Qualitative explanation for the gradient mechanism in terms of the inhomogeneous critical state under field cycling is presented. Reconstruction of one-dimensional EPR images for model samples is presented at low temperatures. Spatial resolution of the order of 1 μm is experimentally reached on a standard X-band continuous-wave EPR spectrometer.