English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Deterministic enhancement of the superconducting (SC) critical temperature$T_c$ is a long-standing goal in material science. One strategy is engineeringa material at the nanometer scale such that quantum confinement strengthens theelectron pairing, thus increasing the superconducting energy gap $\Delta$, aswas observed for individual nanoparticles. A true phase-coherent SC condensate,however, can exist only on larger scales and requires a finite phase stiffness$J$. In the case of coupled aluminium (Al) nanograins, $T_c$ can exceed that ofbulk Al by a factor of three, but despite several proposals the relevantmechanism at play is not yet understood. Here we use optical spectroscopy ongranular Al to disentangle the evolution of the fundamental SC energy scales,$\Delta$ and $J$, as a function of grain coupling. Starting from well-coupledarrays, $\Delta$ grows with progressive grain decoupling, causing theincreasing of $T_c$. As the grain-coupling is further suppressed, $\Delta$saturates while $T_c$ decreases, concomitantly with a sharp decline of $J$.This crossover to a phase-driven SC transition is accompanied by an optical gappersisting above $T_c$. These findings identify granular Al as an idealplayground to test the basic mechanisms that enhance superconductivity bynano-inhomogeneity.

Shaping a superconducting dome: Enhanced Cooper-pairing versus suppressed phase coherence in coupled aluminum nanograins