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DOE OSTI · 3384971

On-Chip Tuning of Superconductivity in Fullerides via Current-Driven Rb + Intercalation

Shchukin, Konstantin P. [Technische Univ. Wien (Austria); Univ. of Cologne (Germany)] (ORCID:000000034766427X)·Gallego Lacey, Oliver N. [Univ. of Grenoble Alpes, Grenoble (France)]·Coquinot, Baptiste [Institute of Science and Technology Austria (ISTA) (Austria)]·Jakowski, Jacek [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000349063574)·Huang, Jingsong [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)] (ORCID:0000000189932506)·Staudenmayer, Patrik [Technische Univ. Wien (Austria)]·Falke, Yannic [Univ. of Cologne (Germany)]·Pandeya, Ram Prakash [Technische Univ. Wien (Austria)]·Grüneis, Alexander [Technische Univ. Wien (Austria)] (ORCID:0000000324486060)
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Abstract

An in-operando electro-intercalation method for the on-chip synthesis of alkali-metal-intercalated materials and their Raman spectroscopic and transport characterization in ultrahigh vacuum (UHV) is developed. We apply this method to synthesize fulleride superconductors via Rb + intercalation into a C 60 film. During the intercalation, we monitor the stoichiometry via UHV-Raman spectroscopy and probe superconductivity via transport measurements. An increase of the superconducting transition temperature from 7.0 K to 14.5 K is observed when the stoichiometry is tuned from Rb 2.7 C 60 to Rb 3 C 60 . In our experiment, an ionic Rb+ flux into the host material is induced by an applied electronic current via a Butler–Volmer-type mechanism. Electro-intercalation captivates through improved stoichiometric precision, the ability to smoothly vary stoichiometry via duration of current application, and the absence of a lower limit of the volume of the host material. It represents a powerful concept for the on-chip synthesis of intercalated materials, battery research, and beyond.

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Shchukin, Konstantin P. [Technische Univ. Wien (Austria); Univ. of Cologne (Germany)] (ORCID:000000034766427X), Gallego Lacey, Oliver N. [Univ. of Grenoble Alpes, Grenoble (France)], Coquinot, Baptiste [Institute of Science and Technology Austria (ISTA) (Austria)], Jakowski, Jacek [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000349063574), Huang, Jingsong [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)] (ORCID:0000000189932506), Staudenmayer, Patrik [Technische Univ. Wien (Austria)], Falke, Yannic [Univ. of Cologne (Germany)], Pandeya, Ram Prakash [Technische Univ. Wien (Austria)], Grüneis, Alexander [Technische Univ. Wien (Austria)] (ORCID:0000000324486060). 2026-06-09. On-Chip Tuning of Superconductivity in Fullerides via Current-Driven Rb + Intercalation. https://doi.org/10.1021/acsnano.6c02466

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DOE OSTI2026

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DOE OSTI2025

Dimensional Reduction Guides Electronic Structure Evolution in the A n Cu 4–n SnS 4 Semiconductor Series

The search for new functional materials with tunable properties remains a central challenge in chemistry, particularly for applications in energy and electronics. In this work, we present a framework for predictive crystal design in alkali metal chalcogenides that enables controlled dimensional reduction of a parent covalent motif, yielding a broad range of electronic structures, which systematically evolve from one parent to the other. We present 11 new members of the A n Cu 4–n SnS 4 family (A = alkali metal; n = 0–4), which reduce the three-dimensional (3D) covalent network of Cu 4 SnS 4 into various 3D, 2D, 1D, and 0D [Cu 4–n SnS 4 ] n− motifs through the substitution of Cu with alkali metals of various radii. The end members of the family set the range in achievable band gaps at 0.99 eV for fully covalent Cu 4 SnS 4 (n = 0) and 3.38 eV for K 4 SnS 4 (n = 4) with 0D [SnS 4 ] n− tetrahedra. As the dimensionality of [Cu 4–n SnS 4 ] n− systematically reduces within A n Cu 4–n SnS 4 (n = 1–3), a stepwise increase in band gap energy occurs through a gradual decrease in the energy of the valence band maximum and an increase in the conduction band minimum, with an increase in the effective masses of charge carriers. Furthermore, irrespective of the alkali metal, the thermal stability decreases with decreasing [Cu 4–n SnS 4 ] n− dimensionality within the quaternary members. Most importantly, we demonstrate that predictable crystal structure and property evolution for a given composition space is possible by deriving a general formula based on substituting the covalent metals of a parent structure with alkali metals.

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DOE OSTI2026

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