Conduction through single Mg and Na atoms linking two macroscopic electrodes

Electrical conduction through single Mg and Na atoms placed between two metallic electrodes is studied. When the atoms are in contact with both electrodes, the resistance of the single-atom wire thus formed is 33 k{Ω} for Na and 12 k{Ω} for Mg. As the electrodes are moved apart, keeping the atom midway, the resistance for the Na case slowly decreases, but that for Mg rises rapidly. Understanding this difference is relevant to a recently proposed type of atomic switch.