Observation of Al2O3: Cr3+ magnetic resonance via solitons in long Josephson junctions

We have detected the zero-field electron-spin resonance signal of Al2O3 with 1000 ppm Cr3+ using an edge Josephson junction. The sample comprises the substrate upon which the junction was fabricated and the coupling to the electron-spin resonance is via the solitons which exist in these "long" devices. © 1987 The American Physical Society.