Fabrication and the transport properties of NbN/Co2Cr0.6Fe0.4Al/NbN lateral junctions

Transport properties of junctions consisting of NbN superconducting electrodes coupled with Co2Co0.6Fe0.4Al (CCFA), a material known for high spin polarization, were investigated. CCFA/NbN bilayers were epitaxially grown on MgO substrate, and then fabricated into NbN/CCFA/NbN lateral junctions by electron-beam lithography. In contrast to the NbTiN/CrO2/NbTiN lateral junction [R.S. Keizer et al., Nature 439 (2006) 825], no Josephson supercurrent through the CCFA channel was observed in our junctions, whose CCFA channel length was 80 nm. A possible explanation for this result is that conversion from spin-singlet Cooper pairs to spin-triplets was strongly suppressed at the NbN/CCFA interface due to the formation of high quality NbN/CCFA interfaces. (C) 2009 Elsevier B.V. All rights reserved.