Physicists have pinpointed a mechanism behind oscillating superconductivity, termed pair-density waves. The revelation, published in Physical Review Letters, sheds light on an unconventional high-temperature superconductive state found in specific materials, including high-temperature superconductors.
Luiz Santos, a physics assistant professor at Emory University and senior study author, explains, “We've uncovered that structures called Van Hove singularities can lead to oscillating superconductivity states. Our research introduces a novel theoretical groundwork for comprehending the origin of this perplexing phenomenon.”
The puzzle of superconductivity
Santos, a theoretical expert in condensed matter physics, delves into the intricacies of quantum materials—microscopic entities such as atoms, photons, and electrons that defy classical physics norms.
One captivating example of quantum behavior is superconductivity, where specific materials conduct electricity sans energy loss upon chilling to ultra-low temperatures. This phenomenon was unveiled in 1911 by Dutch physicist Heike Kamerlingh Onnes, who revealed that mercury shed its electrical resistance at 4 Kelvin or around minus 371 degrees Fahrenheit, akin to Uranus' frigid realm.
The puzzle of superconductivity's existence and mechanisms persisted until 1957, when scientists finally unveiled its secrets. At typical temperatures, electrons meander with relative independence, colliding with other particles, inducing energy dissipation. Yet, under frigid conditions, electrons can unify into an original form of matter.
“They combine into pairs that unite as a collective entity,” Santos clarifies. “Imagine them as soldiers in formation. When isolated, they're easily swayed, but in synchronized procession, their resilience is formidable. This unified state effortlessly carries electric current.”
A holy grail of physics
The potential of superconductivity is immense. In principle, it could enable electric current to flow through wires without generating heat or losing energy, paving the way for significantly enhanced electricity transmission efficiency.
“Attaining practical room-temperature superconductivity is a coveted goal in physics,” notes Santos, emphasizing the transformative impact such a breakthrough could have on society. “It has the power to reshape civilization.”
Frontline physicists and engineers are dedicatedly pushing boundaries to revolutionize electricity transfer methods.
Already, superconductivity has found practical applications. Superconducting coils energize electromagnets in magnetic resonance imaging (MRI) devices, aiding medical diagnoses. A few magnetic levitation trains utilize superconducting magnets, 10 times stronger than regular electromagnets, to generate repelling forces for levitation and propulsion.
The Large Hadron Collider, a particle accelerator probing the universe's fundamental structure, relies on superconductivity for operation.
Further discoveries of superconductivity are ongoing, encompassing materials that maintain this behavior at elevated temperatures.
An accidental discovery
Santos' research zooms in on the intriguing realm where electron interactions give birth to superconductivity forms that defy the 1957 explanation. A prime example of this enigmatic phenomenon is oscillating superconductivity, where partnered electrons engage in rhythmic waves, altering their amplitudes.
In an independent venture, Santos tasked Castro with scrutinizing distinct attributes of Van Hove singularities—structures where numerous electronic states cluster in energy proximity. Castro's investigation unveiled a tantalizing link between these singularities and the inception of oscillating superconductivity.
This revelation spurred Santos and his colleagues into deeper exploration. Their efforts unveiled a mechanism enabling these dance-like superconducting states to originate from Van Hove singularities.
“As theoretical physicists, we aspire to predict and categorize behavior, unraveling nature's mysteries,” Santos explains. “This comprehension paves the way for relevant technological inquiries.”
Some high-temperature superconductors, which function in temperatures about three times colder than a household freezer, exhibit this dance-like behavior. The revelation of its connection to Van Hove singularities provides a bedrock for experimentalists to plumb the possibilities it offers.
“Kamerlingh Onnes likely didn't envision levitation or particle accelerators when he uncovered superconductivity,” muses Santos. “Yet, every facet we learn about the world harbors potential applications.”
Source: Emory University