Spintronics research. Coloured scanning tunnelling micrograph (STM) showing repulsion between manganese atoms in a gallium arsenide semiconductor (blue). The spins of the atoms interact via a cloud of electrons (red and yellow). Gallium atoms in the semiconductor have been substituted by manganese atoms using the scanning tunnelling microscope, which allows precise substitution one atom at a time. This creates a magnetic semiconductor that would be able to store data as well as process it. This research is being carried out by Prof. Yazdani at Princeton Nanoscale Microscopy Laboratory (PNML), Princeton University, USA.