Scientists Find 'Ghost' of Superconductivity in New Material

Topic: Physics

Physicists at the University of Illinois have discovered a new form of superconducting behavior in uranium ditelluride. They found that Cooper pairs, which are paired electrons, can arrange themselves into uneven patterns even when the material is no longer in its main superconducting state.

Superconductivity occurs when a metal can carry electricity with zero resistance after being cooled below a critical temperature. In this state, the material's free electrons settle into a low-energy quantum state.

In 1957, Illinois physicists John Bardeen, Leon Cooper and Robert Schrieffer explained superconducting behavior with what became known as BCS theory. According to their model, electrons first become correlated through interactions with the metal's underlying lattice. One electron then pairs with another to create a Cooper pair. Unlike individual electrons, Cooper pairs behave as bosons.

However, some materials do not fit the assumptions behind BCS theory. These are called unconventional superconductors. The new research focuses on one such material, uranium ditelluride (UTe2). Physicists at the University of Illinois have discovered that in UTe2, Cooper pairs can arrange themselves into uneven patterns even when the material is no longer in its main superconducting state. These patterns are called pair density waves (PDWs).

The researchers used a scanning tunneling microscope to study the behavior of electrons in UTe2. They found that PDWs persist above the temperature at which superconductivity disappears, a phenomenon predicted by theory but never observed before.

Why It Matters

This discovery can help us understand how unconventional superconductors work and may lead to new technologies for energy transmission and storage.

Key Facts

• Physicists at the University of Illinois have discovered pair density waves (PDWs) in uranium ditelluride (UTe2).
• PDWs are uneven patterns formed by Cooper pairs, which persist above the temperature at which superconductivity disappears.
• The discovery was made using a scanning tunneling microscope and is consistent with theoretical predictions.
• Unconventional superconductors like UTe2 do not fit the assumptions behind BCS theory, which explains conventional superconducting behavior.
• BCS theory was developed by John Bardeen, Leon Cooper and Robert Schrieffer in 1957.

Key Terms

Cooper pairs

Paired electrons that behave as bosons and can condense into a superconducting state.

BCS theory

A model developed by John Bardeen, Leon Cooper and Robert Schrieffer in 1957 to explain conventional superconducting behavior.

Implications

This discovery can help us understand how unconventional superconductors work and may lead to new technologies for energy transmission and storage.