Physicists have used a novel measuring technique to track the motions of electron spins in a tiny magnet as its polarity flips, with north and south poles changing places. Magnetic data recording relies on such reversals to encode bits of data.
At the atomic level, magnetism arises from the intrinsic spin of a material's electrons. Polarity can be flipped by applying a magnetic field to reverse the spin of each electron. The spin's axis spirals away from its initial alignment and into its new one, says Can-Ming Hu of the University of Manitoba in Winnipeg.
Physicists usually detect this motion, called precession, by beaming finely tuned microwaves at the sample and measuring electromagnetic feedback. However, Hu says, picking up that feedback becomes increasingly difficult as the sample size shrinks.