Melting behavior of nanoscale indium islands

We have measured the melting temperature and hysteresis for nanoscale indium islands on a WSe₂ substrate. These are self-organized nanostructures whose diameter can vary between about 20 and 200 nm, depending on deposition conditions. By adding trace quantities of radioactive ^111In we observe perturbed angular correlation (PAC) spectra for these tiny islands which distinguish clearly between the solid and liquid states. This technique is almost unique in its sensitivity and ability to see the melting of structures of such small size. The melting point decreases as the islands get smaller due to surface energy. Supercooling and the resulting hysteresis are also observed. We present preliminary data showing the feasibility of the technique.