Metallic low-temperature resistivity in a 2D electron system over an extended temperature range

We report measurements of the zero-field resistivity in a dilute 2D electron system in silicon at temperatures down to 35 mK. This extends the previously explored range of temperatures in this system by almost an order of magnitude. On the metallic side, the resistivity near the metal-insulator transition continues to decrease with decreasing temperature and shows no low-temperature upturn. At the critical electron density, the resistivity is found to be temperature independent in the entire temperature range from 35 mK to 1 K.