Measurement of the currentphase relation in Josephson junction rhombi chains
Abstract
We present lowtemperature transport measurements in onedimensional Josephson junctions rhombi chains. We have measured the currentphase relation of a chain of eight rhombi. The junctions are either in the classical phase regime with the Josephson energy much larger than the charging energy, E_{J}≫E_{C} , or in the quantum phase regime where E_{J}/E_{C}≈2 . In the strong Josephson coupling regime ( E_{J}≫E_{C}≫k_{B}T ) we observe a sawtoothlike supercurrent as a function of the phase difference over the chain. The period of the supercurrent oscillations changes abruptly from one flux quantum Φ_{0} to half the flux quantum Φ_{0}/2 as the rhombi are tuned in the vicinity of full frustration. The main observed features can be understood from the complex energy ground state of the chain. For E_{J}/E_{C}≈2 , we do observe a dramatic suppression and rounding of the switching current dependence which we found to be consistent with the model developed by Matveev [Phys. Rev. Lett. 89, 096802 (2002)] for long Josephson junctions chains.
 Publication:

Physical Review B
 Pub Date:
 September 2008
 DOI:
 10.1103/PhysRevB.78.104504
 arXiv:
 arXiv:0803.3310
 Bibcode:
 2008PhRvB..78j4504P
 Keywords:

 74.40.+k;
 74.50.+r;
 74.81.Fa;
 73.23.b;
 Fluctuations;
 Tunneling phenomena;
 point contacts weak links Josephson effects;
 Josephson junction arrays and wire networks;
 Electronic transport in mesoscopic systems;
 Condensed Matter  Mesoscale and Nanoscale Physics;
 Condensed Matter  Superconductivity
 EPrint:
 to appear in Phys. Rev. B