Universality of the Kondo effect in quantum dots with ferromagnetic leads", describing results that we've been working on during the last months, was just accepted for publication in Physical Review Letters.
So what is it about, in a few simple words?
In general, much of our work is about charges trapped inside carbon nanotubes at very low temperatures (0.05K). Such a trap for e.g. electrons is called a quantum dot; similar to the electron shell of an atom or molecule, the laws of quantum mechanics force the electrons to occupy specific discrete levels, or quantum states. By looking at a tiny tunnel current through a quantum dot we can characterize its quantum mechanical properties; this is called transport spectroscopy.
The Kondo effect is a special case, as it is caused by strong interaction between localized charges inside the quantum dot and charges in the leads that we attach to the quantum dot. Whenever the localized charge can assume either of two (or more) states with equal energy ("degenerate states") and these states all couple to the leads, the Kondo effect causes an extra electrical conductance through the system. This is one of the simplest many particle effects in quantum mechanics and has fascinated researchers for quite some time; its behaviour is called universal, as it is independent of many detailed properties of the system at hand. In a non-magnetic system, the degenerate states are usually given by different directions of the electron internal magnetic moment, its spin.
Now, we contact our nanotube quantum dot with magnetic contacts. In these contacts, 1) the different directions of spin can couple differently to the quantum dot, and 2) the number of charges with one spin direction differs from the other (that's just what makes them magnetic). Among other things, we've been able to show that all this modification just acts on the Kondo effect the same way as an (imagined) magnetic field, so by applying the reverse magnetic field with an external magnet coil, we can restore the universal behaviour as known from non-magnetic systems. This makes the system much easier to describe, and will, we hope, be useful for future work in spintronics, where the magnetic moments are to be used for information processing.
"Universality of the Kondo effect in quantum dots with ferromagnetic leads"
M. Gaass, A. K. Hüttel, K. Kang, I. Weymann, J. von Delft, and Ch. Strunk
accepted for publication by Physical Review Letters; arXiv:1104.5699 (PDF)
Note: the Wikipedia articles "quantum dot" and "Kondo effect" are not wrong, but describe special uses of these terms and not the most general case as known today. Unfortunately this makes them completely useless as references here...