Using a SQUID magnetometer, changes in the nuclear magnetization of copper are observed when the nuclear spins absorb rf power at resonance. Since the detected flux change is directly proportional to the change in static magnetizationΔM, this method offers higher sensitivity at low frequencies than conventional NMR which responds todM/dt. The experimental arrangement for observingΔM at temperatures below1 K is described. The variation of signal amplitude with temperature and rf power is found to agree well with predictions from the Bloch equations. A comparison of the sensitivity of the SQUID magnetometer and conventional NMR methods shows the advantage of the new technique at low frequencies and for nuclear systems with broad lines and long spin-lattice relaxation times.
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Meredith, D.J., Pickett, G.R. & Symko, O.G. Application of a SQUID magnetometer to NMR at low temperatures. J Low Temp Phys 13, 607–615 (1973). https://doi.org/10.1007/BF00656548
- Relaxation Time
- Magnetic Material
- Signal Amplitude
- Experimental Arrangement