Study Provides New Insights on Superconductors and Their Potential Applications

May 13, 2020 by Luke James

To date, several rigorous studies have demonstrated that high temperature superconductors have many applications and are capable of transforming the technologies of today.

Despite these studies, there is still a significant lack of understanding that is needed to develop these materials for use in widespread applications like quantum computing. “Higgs spectroscopy”, however, could bring about a watershed as it reveals the dynamics of paired electrons in superconducting materials. 

An international research consortium centered around the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and the Max Planck Institute for Solid State Research (MPI-FKF) presented its new measuring method.


High Temperature Superconductors

While superconductors are remarkable and could be a game-changer for electronics by dramatically reducing energy requirements, they require temperatures of -140 degrees Celsius and below—superconductors only “turn on” their superconductivity below this point.

Unfortunately, this makes them impractical for a plethora of otherwise useful applications because, in most cases, reaching this temperature is either inefficient or impossible depending on the application. 

There is a promise of progress in innovative materials based on copper oxide, known as “cuprates”. These are high temperature superconductors made of layers of copper oxides that alternate with charge reservoirs, which are oxides of other metals.

They were discovered in 1986—kicking off the so-called “copper age of superconductivity—and already have large-scale applications, the most famous example, of course, being that of the superconducting wires found in the Large Hadron Collider at CERN. Despite many years of research, however, cuprates’ exact mode of operation remains unclear. 


A New Insight Into High-Temperature Superconductivity

In superconductivity, electrons form “Cooper pairs” which allows them to move through the material without interacting with the environment. In conventional superconductors, we know that electrons of the same charge pair up because of crystal lattice vibrations.

One electron distorts the lattice which then attracts the second. In cuprates, however, it is not clear what makes the electrons pair up in the absence of these lattice vibrations.  

"Higgs spectroscopy offers us a whole new 'magnifying glass' to examine the physical processes," Dr. Jan-Christoph Deinert reports. What the researchers want to discover is the mechanism for these pairings in cuprates. And Higgs spectroscopy has enabled the research consortium to achieve their experimental breakthrough for cuprates. 


Graphic of terahertz pulse affect to superconductor.

By applying a strong terahertz pulse, the research team was able to decipher previously invisible dynamics in superconductors. Image credited to HZDR / Juniks


Combining High-Intensity Terahertz Pulse To Drive the Higgs Approach

The researchers used a multi-cyclic, extremely strong terahertz pulse that is optimally tuned to Higgs oscillation and can maintain it despite the damping factors. With the high-performance terahertz light source TELBE at HZDR, the researchers are able to send 100,000 pulses through the samples per second.

"Our source is unique in the world due to its high intensity in the terahertz range combined with a very high repetition rate," Deinert explains. "We can now selectively drive Higgs oscillations and measure them very precisely."

“Higgs spectroscopy as a methodical approach opens up entirely new potentials,” said Dr. Hai Chu, the study’s primary author. The research team expects to see a high demand in the future for its systematic approach because it is the starting point for a series of potential experiments that will provide us with new insights into cuprates.  


New Technologies Enabled by High-Temperature Superconductivity

By being able to truly understand high-temperature superconductors and create a material from them that could easily be made into wires, for example, staggering new technologies would soon follow.

For starters, it would transform the way we transmit and use electricity by making it a whole lot more efficient and consume less power. High-temperature superconductivity would also be a boon for renewable energy applications because transporting electricity over long distances would become simpler. 

However, until high-temperature superconductivity becomes stable enough for real-world applications—whether this is achieved by a cuprate, magnesium diboride, or an iron-based superconductor—many superconducting technologies will stay on the drawing board.