Researchers use superconductor material KTaO3 to develop high magnetic field-resistant films

Magnetic fields limiting potential

However, many conventional superconductors lose their superconductive functions when exposed to magnetic fields; as a result, it limits their potential. 

Kaveh Ahadi, the study’s corresponding author and an assistant professor of materials science and engineering at North Carolina State University, said, “Our work here is important because not only have we demonstrated how to fabricate high-quality KTaO3, but we have also shown that the material is capable of withstanding substantial magnetic fields without losing its desirable properties,” 

“Specifically, we found that KTaO3 retains superconductivity even when exposed to magnetic fields up to 25 Tesla. This fundamental work is a necessary step toward the development of any potential applications for the material,” added Ahadi.

The scientists developed a method to grow KTaO3 using a technique called molecular beam epitaxy which effectively constructed two-dimensional (2D) thin films of the superconductive material on a substrate. Researchers laid down molecule-thin layers on top of one another with atomic-level precision, a statement explained. 

'Very few defects'

As a result, high-quality thin films were formed, implying that the molecular structure of the new material has very few defects, the study claims.

“These high-quality thin films are an ideal platform for studying the intrinsic properties of this materials system,” Ahadi stated.

A statement by the researchers said that upon conducting a characterization, they found that KTaO3 thin films remained superconductive when exposed to magnetic fields of up to 25 Tesla. Such a magnetic field can only be generated in the United States at the National High Magnetic Field Laboratory, where the material was tested. 

Ahadi said, “The research community is still in the early stages of understanding the superconductivity in KTaO3, much less identifying applications for the material. Our work here not only identifies one attractive quality that sets it apart from other 2D superconductors but provides a blueprint for how we can create KTaO3 thin films that are well suited for performing the research necessary to understand intrinsic properties of this materials system.”

The research was covered in three journal articles, with the latest study published in Nano Letters on July 27.  

Abstract:

The nature of superconductivity and its interplay with strong spin–orbit coupling at the KTaO3(111) interfaces remain a subject of debate. To address this problem, we grew epitaxial LaMnO3/KTaO3(111) heterostructures. We show that superconductivity is robust against the in-plane magnetic field, with the critical field of superconductivity reaching ∼25 T in optimally doped heterostructures. The superconducting order parameter is highly sensitive to the carrier density. We argue that spin–orbit coupling drives the formation of anomalous quasiparticles with vanishing magnetic moment, providing significant condensate immunity against magnetic fields beyond the Pauli paramagnetic limit. These results offer design opportunities for superconductors with extreme resilience against the applied magnetic fields.