Superconductivity persists in a 5 nm iron chalcogenide flake
The transition temperature fell only slightly, while the field required to suppress superconductivity depended strongly on its orientation.
Fangdong Tang and colleagues exfoliated FeTe₀.₅₅Se₀.₄₅ crystals into thin devices. At 5 nm the flake thickness approached the superconducting coherence length, yet its transition temperature stayed close to that of bulk crystals.
The magnetic field needed to suppress superconductivity differed markedly when applied parallel or perpendicular to the flake. Transport and point-contact measurements supported a quasi-two-dimensional superconducting state. Liyuan Zhang at SUSTech co-authored the paper.