HIGH-SENSITIVITY MAGNETIC-RESONANCE BY SQUID DETECTION

A SQUID magnetometer has been used to detect electron paramagnetic resonance of the Ce%3 ion in dilute CMN (1 %) at low temperatures down to 10 mK. This method of detecting magnetic resonance allows a greater signalto-noise ratio over conventional methods with samples having long Τ1 and short Τ2 values and it is particularly useful at very low temperatures. Resonance experiments can be simply performed without apparatus modification at rf frequencies ranging from about 10 kHz to well above 1 GHz, thus making it possible to observe low-field EPR as well as NMR signals from the same sample. Spin lattice relaxation measurements, using this method, on both powdered and single-crystal 1% CMN show a low-temperature phonon bottleneck behavior consistent with previous measurements. Relaxation in the powder is much faster than that observed in the single crystal. © 1979 Plenum Publishing Corporation.