Unconventional superconductivity induced in s-wave superconductors by adsorbed chiral molecules


  Hen Alpern  ,  Prof. Oded Millo  ,  Prof. Yossi Paltiel  ,  Prof. Nadav Katz  ,  Dr. Hadar Steinberg  ,  Dr. Shira Yochelis  ,  Eran Katzir  ,  Tom Dvir  
Racah Institute of Physics, Hebrew Univeristy Jerusalem Israel
Department of Applied Physics, Hebrew Univeristy Jerusalem Israel

Following recent discoveries regarding the unique properties of chiral molecules which serve as spin filters and induce spontaneous magnetization, we investigated the effect of chiral molecules on singlet s-wave superconductors. Using scanning tunneling spectroscopy on thin Nb films coated with chiral polyalanine alpha-helix molecules we found evidence for the emergence of a triplet-pairing chiral p-wave superconducting component. Following these results, we performed Andreev spectroscopy measurements on thin NbSe2 flakes exfoliated over Au electrodes before and after chiral molecules adsorption. Upon adsorption, the differential conductance spectra change their shape significantly, and in particular exhibit a narrow and pronounced zero bias conductance peak, which vanishes above T ~ 0.5TC and parallel magnetic fields well below HC2 of NbSe2. These measurements provide further evidence for the emergence of unconventional superconducting order-parameter upon chiral molecule adsorption.  The accumulation of evidence for the ability of chiral molecules to alter the symmetry of conventional superconductors may open a novel way for realizing simple superconducting spintroinics devices.