Inducing odd-frequency triplet superconducting correlations in a normal metal strip

Hybrid superconducting/ferromagnetic circuits can exhibit fascinating unconventional superconducting correlations. A conventional superconductor hosts Cooper pairs made out of two electrons correlated in a spin-singlet state. However, a ferromagnet contacted to a superconductor can contain triplet superconducting correlations. These correlations are related to those observed in exotic compounds like SrRuO4. Synthesizing and controlling such correlations in artificial nanostructures is therefore an important goal. When the ferromagnet has a non-homogeneous magnetization, two types of triplet superconducting correlations can appear: correlations with total spin 0 (between opposite spins) and correlations with total spin 1 (between equal spins). Triplet correlations with spin 0 have been observed a decade ago. However, indirect signatures of triplet correlations with spin 1 have been observed only recently. In this talk, I will present a new geometry where triplet superconducting correlations would propagate inside a normal metal strip contacted to a superconductor and a ferromagnetic insulator [1]. I will use spin-dependent boundary conditions for isotropic superconducting Green's functions [2] to calculate the density of states inside the normal metal strip. This signal would provide a more direct characterization of superconducting correlations. In particular, it would enable an unambigous characterization of triplet correlations with spin one. [1] A. Cottet, Phys. Rev. Lett. 107, 177001 (2011). [2] A. Cottet, D. Huertas-Hernando, W. Belzig, and Y. V. Nazarov, Phys. Rev. B 80, 184511 (2009)