Penn State team reveals superconductivity in FeTe, then tunes it with a moiré interface

Researchers at Penn State have reported that iron telluride, or FeTe, is superconducting once hidden excess iron is removed, overturning a long-standing view that the compound was only a magnetic metal. In a second paper published alongside the first on April 1, 2026, the team showed that the superconducting state can also be modulated by adding a different thin layer on top, creating a moiré superlattice at the interface.

Stoichiometric FeTe turns superconducting at 13.5 Kelvin

The central finding is straightforward and unusual: a thin film of FeTe, grown by molecular beam epitaxy, became superconducting after the researchers used tellurium vapor to compensate for excess iron atoms trapped in the crystal structure. The team reported a critical temperature of about 13.5 Kelvin, or roughly minus 435 degrees Fahrenheit.

FeTe had long been grouped with magnetic metals rather than superconductors. The new work suggests that disorder in the lattice was masking the material’s intrinsic behavior, and that restoring the ideal iron-to-tellurium ratio exposes a zero-resistance state.

A moiré superlattice reshapes the superconducting pattern

After establishing that the material can superconduct, the researchers went one step further. They grew a second layer with a different crystal structure on top of FeTe, producing a moiré superlattice at the interface. Using scanning tunneling microscopy, they observed that superconductivity formed a repeating, droplet-like pattern that tracked the larger atomic-scale interference pattern.

The pattern was not fixed. According to the team, it could be adjusted by changing the top layer, pointing to a practical control knob for how superconductivity is distributed across the film.

Why the result matters for 2D materials research

FeTe is not a consumer product story, but it is a meaningful materials-science milestone. Two-dimensional materials and ultrathin films have long promised exotic electronic behavior, yet many candidate systems are held back by disorder, interfaces and fabrication sensitivity. This work addresses all three at once: it identifies a hidden superconducting phase, shows how to stabilize it, and then demonstrates that an engineered interface can reshape it.

That combination is relevant to quantum materials design, where researchers are increasingly trying to move from discovering unusual states to controlling them with atomic precision. For now, the important point is that the new papers turn FeTe from a presumed dead end into a tunable superconducting platform.