Ultrafast superconducting vortices exposed

 

Claiming a world first, researchers have used a nanoscale scanning superconducting quantum interference device to directly observe and measure ultra-fast vortex dynamics in superconductors.

 

The novel method is set to be used to test designs for reducing vortex motion and improving superconductors' properties.

 

Understanding when and how superconducting vortices will move within a material and increase electrical resistance is the focus of much scientific research, but addressing the physics of fast moving vortices experimentally has proven challenging due to a lack of adequate tools.

 

Given this, Professor Eli Zeldov from the Weizmann Institute of Science, Dr Yonathan Anahory from the Hebrew University of Jerusalem's Racah Institute of Physics, and colleagues, used a novel microscopy method developed at the Weizmann Institute to reveal how these vortices move in superconducting materials.

 

 

The so-called scanning SQUID-on-tip is a magnetic sensing device fabricated on a sharp nanotip, that can measure and image magnetic fields at unprecedented high resolution - around 50 nm - and magnetic sensitivity.

 

Using a scanning SQUID-on-tip microscope, the researchers observed vortices flowing through a thin superconducting film at rates of tens of GHz, and travelling at velocities much faster than previously thought possible; up to about 72 000 km/hr (45 000 mph).

 

Imaging shows how the vortex trajectories appear as smeared lines crossing from one side of the film to another, similar to the blurring of images in photographs of fast-moving objects.

 

 

The images also show a tree-like structure with a single stem that undergoes a series of bifurcations into branches.

 

According to the researchers, this channel flow is quite surprising since vortices normally repel each other and try to spread out as much as possible. Here vortices tend to follow each other, which generates the tree-like structure.

 

 

"This work offers an insight into the fundamental physics of vortex dynamics in superconductors, crucial for many applications," says lead researcher Dr Lior Embon from the Weizmann Institute of Science. "These findings can be essential for further development of superconducting electronics, opening new challenges for theories and experiments in the yet unexplored range of very high electromagnetic fields and currents."

 

"The research shows that the SQUID-on-tip technique can address some outstanding problems of non-equilibrium superconductivity, ultrafast vortices and many other magnetic phenomena at the nanometer scale," adds Anahory, senior lecturer at the Hebrew University's Racah Institute of Physics.

 

Research is published in Nature Communications.