Atomic magnetometers for materials characterization

Sensitive magnetometry has been established as a powerful technique for the characterization and testing of materials, with the most demanding applications relying on SQUID magnetometers operating at cryogenic temperatures. The recent development of compact, non-cryogenic atomic magnetometers with sub-femtotesla sensitivity and easy sample access has opened up a number of new possibilities. We give examples of sample thermal demagnetization measurements with sensitivity better than 10−9 emu/Hz½ up to 420 °C and of magnetic detection of water droplets on an aluminum surface. Recent research on magnetometry with laser-cooled atoms and color centers in diamond promises to extend the reach of atomic magnetic sensors to the micro- and nanoscale.