The search for a superconductor that can operate at everyday temperatures and pressures has long been an elusive goal in the field of superconductivity. The potential impact of such a discovery on various aspects of modern life cannot be overstated. However, current high-temperature superconductors still require extremely cold temperatures to function effectively, making them impractical for most applications. The complex nature of superconductors, involving intricate magnetic and electronic states that intertwine and compete with each other, presents a challenge for scientists trying to achieve room-temperature superconductivity. In a recent breakthrough, scientists from the U.S. Department of Energy’s Brookhaven National Laboratory, Columbia University, and Japan’s National Institute of Advanced Industrial Science and Technology have made significant progress in this area. Their discovery challenges prevailing beliefs about superconductors and opens up new avenues for research and potential applications.
In a paper published in the journal Nature on June 28, 2023, the team reported their groundbreaking observation of a pair density wave (PDW) in an iron-based superconducting material, even in the absence of a magnetic field. This finding challenges the prevailing belief that PDWs only occur in the presence of a large magnetic field. Kazuhiro Fujita, a physicist at Brookhaven involved in the study, expressed excitement about the results, stating that previous evidence for a zero-magnetic-field PDW had been ambiguous at best. This discovery in the iron pnictide EuRbFe4As4 (Eu-1144) material opens new avenues for research and potential breakthroughs in superconductivity.
Eu-1144 possesses a layered crystalline structure, and it naturally exhibits both superconductivity and ferromagnetism. This unique characteristic intrigued the researchers, leading them to delve deeper into understanding the relationship between magnetism and superconductivity. Magnetic order typically destabilizes superconductors, making the coexistence of both phenomena within a single compound particularly fascinating.
To investigate Eu-1144, the team utilized a state-of-the-art spectroscopic-imaging scanning tunneling microscope (SI-STM) at Brookhaven’s ultra-low vibration laboratory. This advanced microscope enables researchers to map the crystal lattice and the distribution of electrons at different energies at each atomic location. By measuring electron tunneling between the sample’s surface and the microscope’s tip, they could observe the behavior of Eu-1144 as its temperature increased. The measurements revealed critical points where magnetism emerged (indicating ferromagnetism) and superconductivity occurred (allowing current flow with zero resistance). Below the critical superconducting temperature, oscillations in the gap representing the energy required to break apart the electron pairs responsible for superconducting current flow were observed, providing direct evidence of a PDW.
The observation of a PDW without the presence of a magnetic field represents a significant leap forward in the quest for room-temperature superconductivity. This breakthrough opens up new possibilities for research and exploration in the field, as scientists can now investigate the replication of this phenomenon in other materials. The development of superconductors that operate at higher temperatures becomes a tangible goal with this new understanding. Additionally, further investigation into PDWs could lead to indirect detection methods for electron pair movement through signatures appearing in other material properties.
Collaboration and future research
The study has garnered significant interest from collaborators in the scientific community, who are already planning various experiments on Eu-1144. Experimentation using X-rays and muons is expected to provide further insights into the material’s behavior. As scientists delve deeper into the nature of PDWs and explore their potential applications, the possibilities for advancing our understanding of superconductivity continue to expand.
The recent breakthrough discovery challenges the prevailing understanding of superconductors and offers valuable insights into the complexities of these materials. The observation of a PDW in an iron-based superconductor without the need for a magnetic field represents a significant step forward in the quest for room-temperature superconductivity. This finding opens up new avenues for further research and discovery, bringing us closer to realizing the dream of practical room-temperature superconductors.
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