Comunicazione
Superconducting order parameter in $NbRe/Co$ hybrids.
Cirillo C., Strohmeier M., Rovirola M., González C., Casals B., Macià F., Hernàndez J.M., Makhdoumi Kakhaki Z., Scheer E., Garcia-Santiago A., Di Bernardo A., Attanasio C.
Non-centrosymmetric superconductors (NCSs) are a fascinating class of materials. The lack of the inversion symmetry in their crystal structure may produce an unconventional superconducting gap, with a mixture of spin-singlet and spin-triplet components. This can open the path to the generation and control of spin-polarized supercurrents, with perspectives in basic research and applications. Here we present the results of the investigation of the superconducting order parameter of NCS NbRe films and NbRe-based ferromagnetic (NCS/F) hybrids by using different experimental techniques. The dependence of the superconducting critical temperature ($T_c$) of NbRe/Co bilayers on the thickness of the Co layer exhibits a very slow decay compared to the behavior of conventional Nb/Co bilayers. Ferromagnetic resonance measurements on NbRe/Co/NbRe trilayers also give unusual results compared to other S/F/S systems, such as an almost unperturbed damping coefficient below $T_c.$ Finally, low-temperature scanning tunnelling microscopy on NbRe and NbRe/Co bilayers reveal a complex dependence of the density of states on the magnetic field. Results and future experiments are discussed.