MPS and ACS with an atomic magnetometer
  We show that a single atomic magnetometer in a magnetically unshielded environment can be used to perform magnetic particle spectroscopy (MPS) and AC susceptometry (ACS) on liquid-suspended magnetic nanoparticles. We demonstrate methods allowing a simultaneous recording of M(H) and dM/dH(H) dependences of samples containing down to 1 $\mu$g of iron. Our results pave the way towards an atomic magnetometer based MPI scanner. 
Simone Colombo, Victor Lebedev, Zoran D. Grujic, Vladimir Dolgovskiy,   and Antoine Weis
physics.bio-ph physics.atom-ph