Orateur
Description
Hybrid structures combining a superconductor (S) with a magnetically inhomogeneous
material (F) are known to generate long-range, spin-polarized (spin-triplet) Cooper pairs
[1]. The magnetic inhomogeneity at S/F interfaces converts singlet and zero-spin-triplet
Cooper pairs into fully polarized spin-triplet Cooper pairs. Experimental support for this
mechanism has been obtained from studies of thin-film multilayers [2], and evidence of
a similar phenomenon has been reported for van der Waals heterostructures combining
the 2D superconductor NbS$_2$ with the intercalated helimagnetic metal Cr$_{1/3}$NbS$_2$ [3].
In this talk, multiple S/F stacks consisting of the transition metal dichalcogenide
superconductor NbSe2 and various helimagnetic materials Cr$_{1/3}$NbS$_2$, Cr$_{1/3}$TaS$_2$,
Mn$_{1/3}$NbS$_2$ [4-5], exfoliated down to roughly 10 to 20 nm are investigated. A strong modulation of the
critical temperature of NbSe$_2$ under an applied magnetic field is observed,
depending on the paired helimagnet. First results on VdW spin-valves (F/S/F’) and Josephson junctions
(S/F/S) are also shown, with the perspective of direct evidence of involvement of fully polarized spin-triplets.
[1] F. S. Bergeret et al, Long-Range Proximity Effects in Superconductor-Ferromagnet Structures, Phys. Rev. Lett. 86, 4096 (2001)
[2] J.W.A. Robinson et al, Controlled Injection of Spin-Triplet Supercurrents into a Strong Ferromagnet, Science 329, 59-61 (2010)
[3] A. Spuri et al, Signature of long-ranged spin triplets across a two-dimensional superconductor/helimagnet van der Waals interface, Phys. Rev. Research 6, L012046 (2024)
[4] C. Zhang et al, Magnetic soliton confinement and discretization effects in Cr$_{1/3}$TaS$_2$
nanoflakes. Rare Metals 41, 3005-3011 (2022).
[5] S.A. Osorio et al, Chiral helimagnetism and stability of magnetic textures in MnNb$_3$S$_6$, Phys. Rev. B 108, 054414 (2023)