Ultra-sensitive magnetometry based on free precession of nuclear spins C. Gemmel, W. Heil, S. Karpuk, K. Lenz, Ch. Ludwig, Yu. Sobolev, K. Tullney, M. Burghoff, W. Kilian, S. Knappe-Grüneberg et al. (5 more) Eur. Phys. J. D, 57 3 (2010) 303-320 Published online: 02 March 2010 DOI: 10.1140/epjd/e2010-00044-5