Researchers have found proof for the existence of superconducting state of matter in a non-magnetic environment.
The discovery of an alternate superconducting state called pair density wave (PDW) in non magnetic environment is expected to open up new potential for superconductivity research. Pair density wave were believed to emerge only when superconductor is kept within huge magnetic field. They are characterized by coupled pair of electrons that are constantly in motion.
The breakthrough was made by scientists from the Brookhaven National Laboratory, Columbia University and Japan’s National Institute of Advanced Industrial Science and Technology.
The Details of Discovery
The team used a spectroscopic –imaging scanning tunneling microscope (SI-STM) to detect spatially modulated superconductivity upon the appearance of magnetism in iron pnictide EuRbFe4 As4 (Eu-1144). Below the critical temperature, a gap was observed in the spectrum of electron energies. This indicates the presence of a pair density wave.
The team used the particular iron-based superconductor due to its ability to have both ferromagnetism and superconductivity, which is rare. They were able to find connection between the two properties.
Abhay Pasupathy, one of the paper’s co-authors and his colleagues had studied Eu-1144 using SI-STM at Brookhaven’s ultra-low vibration laboratory.
Kazuhiro Fujita, Brookhaven Lab physicist, said that they were able to create a map of both the sample’s crystal lattice and the number of electrons at different energies at each atomic locations with the measurements of number of electrons at a specific location in the material tunnel back and forth between the sample’s surface and the tip of the SI-STM as voltage between tip and surface is varied. SI-STM makes the measuring possible.
According to Fujita, researchers had theorized the existence of pair density wave on its own. But iron pnictide EuRbFe4As4 is the first material with evidence that indicates the existence of a zero-magnetic-field pair density wave.
Superconductors require very cold temperature to function. This makes it useless in majority of applications.
Still, a lot remains to be done before the realization of room-temperature superconductivity.
