Proximity-induced triplet superconductivity in systems comprising ferromagnets, graphene and chiral-molecules

Seminar
QUEST Center event
No
Speaker
Prof. Oded Millo, Racah Institute of Physics, The Hebrew University of Jerusalem
Date
26/06/2017 - 13:30Add to Calendar 2017-06-26 13:30:00 2017-06-26 13:30:00 Proximity-induced triplet superconductivity in systems comprising ferromagnets, graphene and chiral-molecules In the vast majority of superconductors, the Cooper pairs are formed from electrons with an antiparallel spin alignment and are in the spin-singlet state. In contrast, there are very few materials that show evidence for the exotic state of triplet superconductivity, in which the Cooper pairs comprise electrons with parallel spins. Such a state was predicted to emerge, under some conditions, at superconductor-ferromagnet (S-F) interfaces, and may be important for superconducting-spintronic devices. First experimental evidence for triplet superconductivity was provided by observations of long-range (much larger than the coherence length in F) spin-polarized supercurrents in S-F-S devices. To address this problem from a different angle, we employed scanning tunneling spectroscopy (STS) on various S-F bilayer systems, and our tunneling spectra reveal long-range penetration of superconducting correlations into the ferromagnet, consistent with spin-aligned triplet-pairing with a p-wave order-parameter symmetry. I will also discuss two other systems that showed clear signatures of p-wave triplet-superconductivity in the tunneling spectra. The first consists of a-helix chiral molecules deposited on Nb (a conventional superconductor), and the second comprises single layer graphene deposited on the electron-doped cuprate superconductor Pr1.85Ce­CuO4.     Building 202 (Physics) room 301 Department of Physics physics.dept@mail.biu.ac.il Asia/Jerusalem public
Place
Building 202 (Physics) room 301
Abstract

In the vast majority of superconductors, the Cooper pairs are formed from electrons with an antiparallel spin alignment and are in the spin-singlet state. In contrast, there are very few materials that show evidence for the exotic state of triplet superconductivity, in which the Cooper pairs comprise electrons with parallel spins. Such a state was predicted to emerge, under some conditions, at superconductor-ferromagnet (S-F) interfaces, and may be important for superconducting-spintronic devices. First experimental evidence for triplet superconductivity was provided by observations of long-range (much larger than the coherence length in F) spin-polarized supercurrents in S-F-S devices. To address this problem from a different angle, we employed scanning tunneling spectroscopy (STS) on various S-F bilayer systems, and our tunneling spectra reveal long-range penetration of superconducting correlations into the ferromagnet, consistent with spin-aligned triplet-pairing with a p-wave order-parameter symmetry. I will also discuss two other systems that showed clear signatures of p-wave triplet-superconductivity in the tunneling spectra. The first consists of a-helix chiral molecules deposited on Nb (a conventional superconductor), and the second comprises single layer graphene deposited on the electron-doped cuprate superconductor Pr1.85Ce­CuO4.  

 

Last Updated Date : 13/06/2017