Precise Measurements in Superconductors

Multinational scientific teams use neutron beams to study superconductors, to understand what causes their amazing properties, which if harnessed effectively, could lead to enormous energy-savings.

Source: Canadian Neutron Beam Centre (CNBC)
Contact: cnbc@cnl.ca
Image: Illustration of the Meissner effect, in which superconductors completely expel external magnetic fields (Piotr Jaworski)

Someday you may travel to work on a train that levitates above its track. Impossible? Not with the almost magical properties of superconductors, which can generate strong magnetic fields and conduct electricity perfectly without losing any energy.

Dr. Vladimir Kozhevnikov (right) and students at the D3 beamline.

Dr. Vladimir Kozhevnikov
(right) and two students at the D3 beamline.

Representing a team of researchers in the United States, Belgium and Switzerland, Dr. Vladimir Kozhevnikov accessed the CNBC to perform first-of-a-kind measurements on these exotic materials. Superconductors completely expel external magnetic fields, which is a key to levitation. More precisely, the magnetic field decreases extremely rapidly, that is, over a distance of nanometres, from the surface into the superconducting material. Measuring exactly how rapidly, however, has proved to be extremely challenging and Dr. Kozhevnikov came to the CNBC after these measurements were attempted at a number of other neutron facilities around the world without success.

At the CNBC, Dr. Kozhevnikov successfully measured the in-depth distribution of the magnetic field just below the surface of three superconductors at near-absolute zero temperatures, which allowed his team to determine key parameters that were not yet known precisely for any superconductor, and thereby test competing theories to explain the interplay between magnetism and superconductivity.

In addition to advancing international research, this experiment was also an occasion for science education and outreach. Dr. Kozhevnikov brought four of his undergraduate students from Tulsa Community College to the CNBC to participate in the experiment and learn first-hand about the role that large scientific user facilities play in enabling research for a broad range of science and technology.

β€œThe people I met at the CNBC were very friendly. They were willing and able to explain the answers to my questions and had the patience to expound upon the topics I did not fully understand,” commented Michael Jensen, one of the visiting students.

doi:10.1103/PhysRevB.87.104508