Jun 17 2010
Nanoscale devices confine electrons and enable manipulation of electron spin—an inherent property akin to the direction in which the particle is rotating. An unexpected mechanism for this control in asymmetric structures has now been reported by Keiji Ono at the RIKEN Advanced Science Institute, Wako, in collaboration with a team of researchers from Japan and Taiwan1.
Artificial systems that trap electrons in a tiny volume can display many of the properties of atoms because they create an analogous series of discrete electron energy levels. “One example is the Zeeman Effect in which an applied magnetic field splits a single electron energy level into two, depending on its spin,” explains Ono.
Taking this analogy further, two closely spaced ‘artificial atoms’ can behave like an artificial molecule. In principle, it is possible to transfer an electron between these atoms by tuning the energy level of an electron in one atom to that of the second by, for example, applying an electric field. Indeed, this phenomenon, known as resonant tunneling, occurs in artificial molecules consisting of two identical atoms. Ono and his team showed, however, that the situation is not so simple in artificial molecules comprising two different atoms.