A counter-intuitive epitaxy strategy produces cleaner superconducting films — a key ingredient for stable qubits.
RIKEN researchers reported a method to create a superconducting thin film from iron telluride (FeTe) — notable because FeTe is not normally superconducting. Their goal is intensely practical: qubits in many hardware platforms depend on superconducting films, and defects/impurities can destabilize quantum states and reduce operation accuracy. The work was published in Nature Communications.Â
The twist: instead of choosing a near-perfect lattice match (the “standard play”), the team grew FeTe on cadmium telluride (CdTe) with a large ~20% mismatch. Surprisingly, microscopy and diffraction analysis indicated a “higher-order” matching mechanism that reduces the structural distortion that typically blocks superconductivity. The resulting film becomes superconducting below 10 K. As a control, they grew FeTe on strontium titanate with a much smaller mismatch (~1.8%) — and that film was not superconducting, strengthening the case that higher-order epitaxy is doing the magic.Â
Conclusions:
If scalable quantum hardware is a war of materials defects vs. coherence, this is ammunition: a pathway to higher-quality superconducting films using an approach that flips conventional “best lattice match” intuition on its head.
