Remote Detection of Earth’s Field Nuclear Magnetic Resonance with a Robust Induction Magnetometer

Performing NMR experiments using the Earth's magnetic field, which would require a robust, low-cost, ultrasensitive induction magnetometer, could enable many remote-sensing applications in geological science. Here implementation of active flux feedback flattens the frequency response of the receiver without compromising the signal-to-noise ratio, permitting detection at frequencies above the self-resonance of the coil. This overcomes the key limitation on the density of windings and thus on intrinsic coil sensitivity. Probe dead times of a few milliseconds at 2 kHz allow the quantification of freely movable fluids in porous rock, which is critical for evaluating subsurface formations.