Research | Collaborazioni Scientifiche | Seminari e Convegni
prof. Angelo Di Bernardo - Department of Physics, University of Konstanz, Germany
Evidence for unconventional superconductivity in a hybrid molecule/superconductor system
prof. Angelo Di Bernardo - Department of Physics, University of Konstanz, Germany
Aula S4 (Edificio F) e Microsoft Teams
The combination of different materials into complex heterostructures often leads to the discovery of unconventional phenomena either in the elemental material components or at the interfaces of these hybrid systems. A typical example is the formation of odd-frequency spin-triplet states at the interface of superconductor (S) and ferromagnet (F) materials, which has led to the development of the research field known as superconducting spintronics [1]. Direct evidence for spin-triplet states in hybrid S/F systems has been demonstrated through various spectroscopy techniques including low-temperature scanning tunnelling spectroscopy (STS) [2-3] and low-energy muon spin rotation (LE-?SR) spectroscopy [4].LE-?SR is an ideal technique to discover novel states in hybrid superconducting heterostructures, since it can resolve very small field deviations (less than 0.1 Gauss) with nanometre-depth resolution in the Meissner screening profile of these hybrid systems compared to the Meissner profile of a conventional bare S. In this talk, I will discuss some recent results that we have obtained [5] demonstrating that that the conventional Meissner screening of Nb thin films is significantly modified upon adsorption of non-magnetic chiral molecules (ChMs) on their surface, in a way that also depends on the direction of the applied magnetic field [5]. The modification is not only limited to the ChMs/Nb interface, as suggested by previous STS studies [6-7], but it is long ranged and occurs over a length scale comparable to the Nb coherence length. Our results supported by a theoretical model suggest that the ChMs act as a spin-active layer inducing the formation of spin-triplet pairs, which paves the way for the usage of this and other similar hybrid molecules/superconducting systems for superconducting spintronic and cryogenic memory applications.
1. J. Linder, J. Robinson, Nat. Phys. 11, 307 (2015).
2. A. Di Bernardo, S. Diesch, Y. Gu, et al., Nature Commun. 6, 8053 (2015).
3. S. Diesch, P. Machon, M. Wolz et al., Nature Commun. 9, 1 (2018).
4. A. Di Bernardo, Z. Salman, X. L. Wang et al., Phys. Rev. X 5, 041021 (2015).
5. H. Alpern, ?. ?mundsen, R. Hartmann et al., Phys. Rev. Mater. 5, 114801 (2021).
6. H. Alpern, E. Katzir, S. Yochelis et al., New J. Phys. 18, 113048 (2016).
7. T. Shapira, H. Alpern, S. Yochelis et al., Phys. Rev. B 98, 214513 (2018)
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