In a surprising discovery, an international team of researchers, led by scientists in the University of Minnesota Center for Quantum Materials using two U.S. Department of Energy (DOE) national user facilities including the Advanced Photon Source, found that deformations in quantum materials that cause imperfections in the crystal structure can actually improve the material’s superconducting and electrical properties. The groundbreaking findings could provide new insight for developing the next generation of quantum-based computing and electronic devices. The research was published in Nature Materials.
“Quantum materials have unusual magnetic and electrical properties that, if understood and controlled, could revolutionize virtually every aspect of society and enable highly energy-efficient electrical systems and faster, more accurate electronic devices,” said study co-author Martin Greven, a Distinguished McKnight Professor in the University of Minnesota’s School of Physics and Astronomy and the Director of the Center for Quantum Materials. “The ability to tune and modify the properties of quantum materials is pivotal to advances in both fundamental research and modern technology.”
Elastic deformation of materials occurs when the material is subjected to stress but returns to its original shape once the stress is removed. In contrast, plastic deformation is the non-reversible change of a material’s shape in response to an applied stress—or, more simply, the act of squeezing or stretching it until it loses its shape. Plastic deformation has been used by blacksmiths and engineers for thousands of years. An example of a material with a large plastic deformation range is wet chewing gum, which can be stretched to dozens of times its original length.
While elastic deformation has been extensively used to study and manipulate quantum materials, the effects of plastic deformation have not yet been explored. In fact, conventional wisdom would lead scientists to believe that “squeezing” or “stretching” quantum materials may remove their most intriguing properties.
In this pioneering new study, the researchers used plastic deformation to create extended periodic defect structures in a prominent quantum material known as strontium titanate (SrTiO3). The defect structures induced changes in the electrical properties and boosted superconductivity.
“We were quite surprised with the results” Greven said. “We went into this thinking that our techniques would really mess up the material. We would have never guessed that these imperfections would actually improve the materials’ superconducting properties, which means that, at low enough temperatures, it could carry electricity without any energy waste.”
Greven said this study demonstrates the great promise of plastic deformation as a tool to manipulate and create new quantum materials. It can lead to novel electronic properties, including materials with high potential for applications in technology, he said.
Greven also said the new study highlights the power of state-of-the-art neutron and x-ray scattering probes in deciphering the complex structures of quantum materials and of a scientific approach that combines experiment and theory. Diffuse neutron scattering experiments were performed on the CORELLI spectrometer of the DOE’s Spallation Neutron Source at Oak Ridge National Laboratory. Diffuse x-ray scattering experiments (Fig. 1) were carried out on the X-ray Science Division Magnetic Materials Group’s beamline 6-ID-D at the DOE’s Advanced Photon Source at Argonne National Laboratory.
“Scientists can now use these techniques and tools to study thousands of other materials,” Greven said. “I expect that we will discover all kinds of new phenomena along the way.”
See: S. Hameed1, D. Pelc1, 2,* Z. W. Anderson1, A. Klein3, R. J. Spieker1, L. Yue4, B. Das1, J. Ramberger1, M. Lukas2, Y. Liu5, M. J. Krogstad6, R. Osborn6, Y. Li 4, C. Leighton1, R. M. Fernandes1 , and M. Greven1**, “Enhanced superconductivity and ferroelectric quantum criticality in plastically deformed strontium titanate,” Nat. Mater. 21, 54 (2022). DOI: 10.1038/s41563-021-01102-3
Author affiliations: 1University of Minnesota, 2University of Zagreb, 3Ariel University, 4Peking University, 5Oak Ridge National Laboratory, 6Argonne National Laboratory
We thank D. Robinson and S. Rosenkranz for assistance with x-ray scattering experiments at the APS. The work at the University of Minnesota was funded by the U.S. Department of Energy (DOE) through the University of Minnesota Center for Quantum Materials, under grant number DE-SC-0016371. The work at Argonne was supported by the U.S. DOE Office of Science-Basic Energy Sciences, Materials Sciences and Engineering Division. A portion of this research used resources at the Spallation Neutron Source, a U.S. DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. D.P. acknowledges support from the Croatian Science Foundation through grant number UIP-2020-02-9494. The work at Peking University was funded by the National Natural Science Foundation of China, under grant number 11874069. Sputtering and contacting of samples was conducted in the Minnesota Nano Center, which is supported by the National Science Foundation through the National Nano Coordinated Infrastructure Network, award number NNCI-1542202. This research used resources from the Advanced Photon Source, a U.S. DOE Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.
© 2020 Regents of the University of Minnesota. All rights reserved.
The U.S. Department of Energy's APS at Argonne National Laboratory is one of the world’s most productive x-ray light source facilities. Each year, the APS provides high-brightness x-ray beams to a diverse community of more than 5,000 researchers in materials science, chemistry, condensed matter physics, the life and environmental sciences, and applied research. Researchers using the APS produce over 2,000 publications each year detailing impactful discoveries, and solve more vital biological protein structures than users of any other x-ray light source research facility. APS x-rays are ideally suited for explorations of materials and biological structures; elemental distribution; chemical, magnetic, electronic states; and a wide range of technologically important engineering systems from batteries to fuel injector sprays, all of which are the foundations of our nation’s economic, technological, and physical well-being.
Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation's first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America's scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC, for the U.S. DOE Office of Science.
The U.S. Department of Energy's Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit the Office of Science website.