Non-local Andreev reflection under ac biasD. S. Golubev1 and A. D. Zaikin1, 2
1 Forschungszentrum Karlsruhe, Institut für Nanotechnologie - 76021, Karlsruhe, Germany, EU
2 I.E. Tamm Department of Theoretical Physics, P.N. Lebedev Physics Institute - 119991 Moscow, Russia
received 17 February 2009; accepted in final form 17 April 2009; published May 2009
published online 19 May 2009
We theoretically analyze non-local electron transport in multi-terminal normal-metalsuperconductornormal-metal (NSN) devices in the presence of an external ac voltage bias. Our analysis reveals a number of interesting effects, such as, e.g., photon-assisted violation of balance between crossed Andreev reflection (CAR) and elastic cotunneling (EC). We demonstrate that at sufficiently small (typically subgap) frequencies of an external ac signal and at low temperatures the non-local conductance of the NSN device turns negative implying that in this regime CAR contribution to the non-local current dominates over that of EC. Our predictions can be directly tested in future experiments.
74.45.+c - Proximity effects; Andreev effect; SN and SNS junctions.
73.23.-b - Electronic transport in mesoscopic systems.
74.78.Na - Mesoscopic and nanoscale systems.
© EPLA 2009