Research Finds Competition Between Superconductivity and Pseudogap in Cuprates
A study reveals how superconductivity competes with an enigmatic pseudogap, potentially aiding advancements in high-temperature superconductors.
Researchers have identified competitive dynamics between superconductivity and a neighboring phase called the pseudogap in copper-oxide materials, known as cuprates. This breakthrough could lead to higher-temperature superconductors, according to findings published in the journal Nature Physics on October 20.
A collaborative team including theorists from the Simons Foundation’s Flatiron Institute and experimentalists from Quebec’s Institut national de la recherche scientifique explored a copper alloy, a type of cuprate. The study examined the behavior of electrons as this material transitioned between superconductivity and the pseudogap state, revealing a complex “quantum brawl” for dominance.
Olivier Gingras, a co-author on the study, stated, “We’re really showing that these states are competing.” He emphasized that suppressing the pseudogap while maintaining superconductivity could lead to advancements in superconducting temperatures.
Superconductivity allows electrical current to flow without resistance below a critical temperature, making it important for various technologies. However, the current superconductors, even the most advanced cuprates, must be kept at temperatures below 151 Kelvin, around minus 188 degrees Fahrenheit. Above this threshold, some cuprates enter the pseudogap phase, where current can flow unevenly, complicating practical applications.
The researchers utilized a technique called angle-resolved photoemission spectroscopy (ARPES) to witness the transition from superconductivity to the pseudogap state. They found that the two states cannot coexist simultaneously, suggesting a clearer path to explore how to retain superconductivity by mitigating the pseudogap’s formation.
Simultaneously, another international team led by physicists from the University of Bristol discovered that a magnetic interaction impacts superconductivity in lanthanum cerium copper oxide, a specific cuprate. Their research indicated that fluctuations in magnetic moments could help pair electrons, although the highest temperatures for superconductivity still require additional investigation.
Caitlin Duffy, a postdoctoral researcher involved in this study, noted that they established a relationship between resistance patterns in the materials and superconductivity, focusing on how increased electron doping influenced this dynamic.
A third study utilizing light to probe bismuth-based cuprates uncovered that an intense laser pulse could disrupt superconductivity, revealing a transient state characterized by the pseudogap. This study challenged the notion that superconductivity forms solely from a coherently established pseudogap, suggesting instead a lively competition between these two phases.
As researchers continue to understand these interactions, they emphasize the need for ongoing work to realize practical applications of superconductivity at higher temperatures.
