Super clean sample of URu₂Si₂

We succeeded in growing a high-quality single crystal of URu ₂Si₂ by the Czochralski pulling method and applying the solid state electro-transport method under ultrahigh vacuum. The sample quality strongly depends on the position in the ingot. For some parts of this ingot, the electrical resistivity, specific heat and de Haas-van Alplhen effect were measured. The electrical resistivity of the surface sample clearly indicates a T-linear temperature dependence below 5 K. The mean free path in this sample was determined by the de Haas-van Alphen effect to be 11000 Å.