Nonequilibrium supercurrent in a mesoscopic four-terminal triplet Josephson junction
1 Department of Physics, Southeast University - Nanjing, 210096, PRC
2 Department of Physics and Materials Science, City University of Hong Kong - Hong Kong, PRC
Received: 15 July 2012
Accepted: 25 August 2012
We investigate theoretically the nonequilibrium (NE) supercurrent flowing in a mesoscopic four-terminal triplet superconductor (TS)/normal metal (N)/triplet superconductor junction, of which the N region is a quantum dot (QD) connected via tunnel barriers to the two TS electrodes and two N electrodes, respectively. We find that both the charge and spin triplet supercurrents could be rapidly suppressed and even reversed by increasing the dc voltage applied across the two N electrodes because of the nonthermal electron energy distribution in the dot, similar to the singlet NE supercurrent in an s-wave superconductor system. The reversed NE triplet supercurrent almost vanishes when the bias equals the TS pair potential as long as the coupling between the N electrodes and the QD is not too weak. This arises from the zero-energy states of the TS Josephson junction making the current-carrying density of states vanish nearly outside the energy gap. It is also shown that in this nonmagnetic system the currents flowing in the N electrodes are spin-polarized and can be modulated by the TS phases owing to the quantum interference effect.
PACS: 74.50.+r – Tunneling phenomena; Josephson effects / 74.45.+c – Proximity effects; Andreev reflection; SN and SNS junctions / 74.78.-w – Superconducting films and low-dimensional structures
© EPLA, 2012