Superconducting materials could play a crucial role in the energy-efficient applications of the future. However, several technical challenges still stand in the way of their practical use. Now, researchers at Chalmers University of Technology in Sweden have developed a new material design that addresses a major obstacle in the field: enabling superconductivity to operate at higher temperatures while also withstanding strong magnetic fields. This breakthrough could pave the way for far more energy-efficient electronics and quantum technologies.
Digital devices, data centres and information and communications technology (ICT) networks currently account for approximately 6 to 12 percent of global electricity consumption. There is a substantial and growing need for more energy-efficient electronics and this is where superconducting materials have emerged as a promising solution. Unlike conventional electronics, which lose energy as heat, superconductors can conduct electricity with zero energy loss. Thus, superconductors have the potential to make power grids, electronics and quantum technologies hundreds of times more energy efficient.
However, the path to real-world applications is still blocked by several key challenges. One major obstacle is that superconducting states often require extremely low temperatures – down to around minus 200 degrees Celsius. Cooling to such temperatures is complex and energy-intensive. Another major challenge is that superconductivity can be weakened or destroyed by strong magnetic fields. This is a critical limitation, as magnetic fields are often present in advanced electronic devices and are essential to many quantum technologies. For superconducting technology to move beyond the laboratory and into practical use, materials are therefore needed that can maintain superconductivity at higher temperatures (ideally close to room temperature), while also remaining robust under strong magnetic fields.
Robust superconductivity via new approach
In the search for these kinds of robust superconductors, researchers in the field have tried modifying the chemical composition of a wide range of materials, with limited success. Now, researchers at Chalmers have tried a different route – and taken an important step forward.
"By sculpting the surface that the superconductor rests on, we were able to induce superconductivity at significantly higher temperatures than previously possible. We also found that the material remained superconducting even when exposed to strong magnetic fields," explains Floriana Lombardi, Professor of Quantum Device Physics at Chalmers and lead author of a study published in Nature Communications.
Tiny detail made a huge difference
The Chalmers researchers used a copper-oxide–based material belonging to the cuprate family. Cuprates are well-known superconductors that can operate at rather high temperatures. However, their chemical structure is difficult to tune after fabrication.
The superconducting material itself, used in this study, is only a few nanometres thick – less than one millionth of a hair's thickness. For practical electronics, such ultrathin films must be deposited on a supporting base, known as a substrate, which provides the necessary template for growth. The breakthrough came when the Chalmers team introduced nanoscale adjustments to the substrate surface.
"Because the atoms in the substrate are arranged in a specific pattern, they can 'guide' how the atoms in the superconducting layer settle. By changing the surface design of the substrate, we were able to influence the superconducting properties and ensure they were preserved, even at higher temperatures and when high magnetic fields were applied," explains Eric Walhberg, a researcher at RISE Research Institutes of Sweden.
When the researchers pre-treated the substrate in a vacuum and at high temperature, a regular surface pattern formed, consisting of tiny ridges and valleys. This pattern created a kind of electronic landscape in the interfacial region between the substrate and the superconducting material – one that favoured stronger superconductivity.
"We could see how the electrons' properties began to have a preferential direction in this interfacial region and behave in a way that stabilised and strengthened the superconducting state," says Lombardi.
A new design principle for future superconductors
With this breakthrough, the researchers introduce a new design principle for developing superconducting materials that may, in the future, reach much higher temperature functionalities, maybe even closer to room temperature.
"Instead of searching for entirely new materials or manipulating the chemical properties of existing ones, we are now showing how superconductivity can be enhanced by sculpting the substrate," says Lombardi.
These results open the door to practical applications of superconductors in energy-efficient electronics, next-generation quantum components and technologies that require strong magnetic fields.
"This shows that very small changes at the nanoscale can have decisive effects and may even unlock the full potential of superconductivity in future electronics," says Lombardi.
More about the study
Boosting superconductivity in ultrathin YBa₂Cu₃O₇−δ films via nanofaceted substrates has been published in the scientific journal Nature Communications. The authors of the study are Eric Wahlberg, Riccardo Arpaia, Debmalya Chakraborty, Alexei Kalaboukhov, David Vignolles, Cyril Proust, Annica M. Black-Schaffer, Thilo Bauch, Götz Seibold and Floriana Lombardi.
The researchers are affiliated with Chalmers University of Technology, RISE Research Institutes of Sweden; Ca' Foscari University of Venice, Italy; Birla Institute of Technology and Science—Pilani, K. K. Birla Goa Campus, India; Indian Institute of Science Education and Research (IISER), India; Uppsala University, Uppsala, Sweden; Université Grenoble Alpes, Université de Toulouse, INSA-T, France; and Institut für Physik, BTU Cottbus-Senftenberg, Germany.
Part of this work was conducted at Myfab Chalmers, a cleanroom facility.
The research project has received support from: The Swedish Research Council (VR), the Knut and Alice Wallenberg Foundation, the EIC Pathfinder grant from the European Union, and the Deutsche Forschungsgemeinschaft.
Caption:
The conceptual image shows how the researchers' sculpted pattern of tiny hills and valleys – smaller than one millionth of a hair's thickness – on the substrate (MgO, at the bottom) guides how the atoms in the superconducting material (YBCO, on top) settle. At the interface between the two layers, an electronic landscape allows superconductivity to occur at higher temperatures than previously possible – even when high magnetic fields are applied. Credit: Chalmers University of Technology / Riccardo Arpaia
