Comparison of the Transition to the Insulating State in Two-Dimensional and One-Dimensional Arrays of Ultrasmall Tunnel Junctions
We have fabricated and measured a two-dimensional (2-D) and a one-dimensional (1-D) array of small aluminum tunnel junctions. The 2-D array is in a previously unexplored regime where the charging energy is much larger than the Josephson coupling energy, x=EC/EJ”l. The I-V characteristics and their dependence on temperature and magnetic field have been investigated at temperatures down to 35mK. The I-V characteristics show a large Coulomb blockade. The low voltage conductance decreases rapidly as the temperature is lowered. Comparison of the 2-D and 1-D case shows a nearly identical temperature dependence in both the superconducting and normal state. Although there is no Josephson current an oscillatory behavior corresponding to one flux quantum (h/2e) per unit cell is observed.
KeywordsSuperconducting State Tunnel Junction Charge Energy Flux Quantum Coulomb Blockade
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- N.Yoshikawa, T.Akeyoshi, M.Kojima, and Sugahara, Ext. Abst. of 1987 Int. Supercond. Electr. Conf. p. 178, (1987)Google Scholar