Researchers have coaxed the tiny particles known as quantum dots to change their magnetic properties simply by shining light on them. The finding is another development in the quest to produce 'spintronic' devices that rely on particles' spin states, rather than their charge, to convey information.
By adding manganese to a chemical suspension, or colloid, of cadmium selenide quantum dots, Daniel Gamelin at the University of Washington in Seattle and his co-workers were able to manipulate the particles' magnetism in new ways. Earlier work had had to be done at ultracold temperatures; the colloidal suspension permitted the particles to power up strong magnetic fields, retaining magnetic signatures even at room temperature.
The researchers say that future steps might include incorporating colloids into nanoparticle manufacturing technologies to see what other effects occur.