Scientists Discover Two Superconducting States Hiding as One in Ultrathin Materials
- Scientists at the Hebrew University of Jerusalem have discovered that niobium diselenide and tantalum disulfide—two ultrathin superconductors long thought to possess a single superconducting state—actually contain two strongly...
- For decades, physicists have investigated superconductors, which are materials capable of carrying electrical current with zero energy loss.
- Using highly sensitive tunneling spectroscopy measurements, the Hebrew University research team found that NbSe2 does not actually behave like a straightforward superconductor governed by a single superconducting order.
Scientists at the Hebrew University of Jerusalem have discovered that niobium diselenide and tantalum disulfide—two ultrathin superconductors long thought to possess a single superconducting state—actually contain two strongly interacting states that masquerade as one. According to findings published in Physical Review Letters, the research resolves a multi-year puzzle regarding the behavior of these materials and could eventually guide the development of improved superconducting materials for quantum computers, ultra-efficient electronics, and advanced sensors.
Uncovering Hidden Complexity in Niobium Diselenide
For decades, physicists have investigated superconductors, which are materials capable of carrying electrical current with zero energy loss. One of the best-studied examples of these materials is niobium diselenide, also known as NbSe2. When researchers reduced the material down to only a few atomic layers, earlier experiments appeared to show relatively simple superconducting behavior. Specifically, the material seemed to feature a single energy gap, which is a key characteristic reflecting how electrons pair together so they can move without electrical resistance. However, traditional theories could not fully reproduce the detailed shape of the superconducting energy spectrum observed in those earlier experiments. Researchers had reason to suspect that the simple picture was incomplete. The study was led by Ph.D. student Shahar Simon and M.Sc. student Maya Klang under the guidance of Prof. Oded Millo and Prof. Hadar Steinberg at the Racah Institute of Physics and the Center for Nanoscience and Nanotechnology at the Hebrew University of Jerusalem.
Two Superconducting Orders Acting as One
Using highly sensitive tunneling spectroscopy measurements, the Hebrew University research team found that NbSe2 does not actually behave like a straightforward superconductor governed by a single superconducting order. Instead, the material contains two distinct superconducting orders that interact so strongly that they appear as a single state. The researchers identified this same concealed behavior in the closely related material tantalum disulfide, or TaS2.
It’s a bit like listening to what sounds like a single singer, only to discover it’s actually a perfectly synchronized duet.
The researchers
By applying a more advanced model that includes two distinct superconducting orders, the team explained the experimental measurements much more accurately than previous methods allowed. This same analytical approach also accounted for how the materials behave when external magnetic fields are applied. Furthermore, the results point toward even greater complexity in thicker forms of the material, suggesting that bulk NbSe2 may contain three interacting superconducting orders.
Implications for Quantum Computers and Advanced Electronics
Uncovering this hidden internal structure gives scientists a clearer view of superconductivity and could eventually allow researchers to design superconducting materials and devices with greater control and precision. As engineers and physicists pursue quantum computers, ultra-efficient electronics, and advanced medical systems, a detailed understanding of how electrons behave inside superconductors will become increasingly important. The discovery demonstrates that some significant scientific surprises emerge not from finding something entirely new, but from taking a closer look at systems researchers thought they already understood.
