Man-made material pushes the bounds of superconductivity

March 03, 2013

MADISON -- A multi-university team of researchers has artificially engineered a unique multilayer material that could lead to breakthroughs in both superconductivity research and in real-world applications.

The researchers can tailor the material, which seamlessly alternates between metal and oxide layers, to achieve extraordinary superconducting properties -- in particular, the ability to transport much more electrical current than non-engineered materials.

The team includes experts from the University of Wisconsin-Madison, Florida State University and the University of Michigan. Led by Chang-Beom Eom, the Harvey D. Spangler Distinguished Professor of materials science and engineering and physics at UW-Madison, the group described its breakthrough March 3, 2013, in the advance online edition of the journal Nature Materials.

Superconductors, which presently operate only under extremely cold conditions, transport energy very efficiently. With the ability to transport large electrical currents and produce high magnetic fields, they power such existing technologies as magnetic resonance imaging and Maglev trains, among others. They hold great potential for emerging applications in electronic devices, transportation, and power transmission, generation and storage.

Carefully layered superconducting materials are increasingly important in highly sophisticated applications. For example, a superconducting quantum interference device, or SQUID, used to measure subtle magnetic fields in magnetoencephalography scans of the brain, is based on a three-layer material.

However, one challenge in the quest to understand and leverage superconductivity is developing materials that work at room temperature. Currently, even unconventional high-temperature superconductors operate below -369 degrees Fahrenheit.

An unconventional high-temperature superconductor, the researchers' iron-based "pnictide" material is promising in part because its effective operating temperature is higher than that of conventional superconducting materials such as niobium, lead or mercury.

The research team engineered and measured the properties of superlattices of pnictide superconductors. A superlattice is the complex, regularly repeating geometric arrangement of atoms -- its crystal structure -- in layers of two or more materials. Pnictide superconductors include compounds made from any of five elements in the nitrogen family of the periodic table.

The researchers' new material is composed of 24 layers that alternate between the pnictide superconductor and a layer of the oxide strontium titanate. Creating such systems is difficult, especially when the arrangement of atoms, and chemical compatibility, of each material is very different.

Yet, layer after layer, the researchers maintained an atomically sharp interface -- the region where materials meet. Each atom in each layer is precisely placed, spaced and arranged in a regularly repeating crystal structure.

The new material also has improved current-carrying capabilities. As they grew the superlattice, the researchers also added a tiny bit of oxygen to intentionally insert defects every few nanometers in the material. These defects act as pinning centers to immobilize tiny magnetic vortices that, as they grow in strength in large magnetic fields, can limit current flow through the superconductor. "If the vortices move around freely, the energy dissipates, and the superconductor is no longer lossless," says Eom. "We have engineered both vertical and planar pinning centers, because vortices created by magnetic fields can be in many different orientations."

Eom sees possibilities for researchers to expand upon his team's success in engineering man-made superconducting structures. "There's a need to engineer superlattices for understanding fundamental superconductivity, for potential use in high-field and electronic devices, and to achieve extraordinary properties in the system," says Eom. "And, there is indication that interfaces can be a new area of discovery in high-temperature superconductors. This material offers those possibilities."
-end-
Funding from the U.S. Department of Energy Office of Basic Energy Sciences, National Science Foundation, and the Air Force Office of Scientific Research supported the researchers' work. Eom's collaborators include Eric Hellstrom's and David Larbalestier's group at Florida State University; and Xiaoqing Pan's group at the University of Michigan.

--Renee Meiller, 608-262-2481, meiller@engr.wisc.edu

University of Wisconsin-Madison

Related Superconductors Articles from Brightsurf:

Progress in electronic structure and topology in nickelates superconductors
Recently, superconductivity was discovered in the hole-doped nickelates, wh ich provide us a new platform to study the mechanism of high-temperature superconductivity.

UCF researcher zeroes in on critical point for improving superconductors
Developing a practical ''room temperature'' superconductor is a feat science has yet to achieve.

Connecting two classes of unconventional superconductors
The understanding of unconventional superconductivity is one of the most challenging and fascinating tasks of solid-state physics.

Superconductors are super resilient to magnetic fields
A Professor at the University of Tsukuba provides a new theoretical mechanism that explains the ability of superconductive materials to bounce back from being exposed to a magnetic field.

New advance in superconductors with 'twist' in rhombohedral graphite
An international research team led by The University of Manchester has revealed a nanomaterial that mirrors the 'magic angle' effect originally found in a complex man-made structure known as twisted bilayer graphene -- a key area of study in physics in recent years.

A new way towards super-fast motion of vortices in superconductors discovered
An international team of scientists from Austria, Germany and Ukraine has found a new superconducting system in which magnetic flux quanta can move at velocities of 10-15 km/s.

Controlling superconductors with light
IBS scientists has reported a conceptually new method to study the properties of superconductors using optical tools.

Superconductors with 'zeitgeist' -- When materials differentiate between past and future
Physicists at TU Dresden have discovered spontaneous static magnetic fields with broken time-reversal symmetry in a class of iron-based superconductors.

Hydrogen blamed for interfering with nickelate superconductors synthesis
Prof. ZHONG Zhicheng's team at the Ningbo Institute of Materials Technology and Engineering has investigated the electronic structure of the recently discovered nickelate superconductors NdNiO2. They successfully explained the experimental difficulties in synthesizing superconducting nickelates, in cooperation with Prof.

A closer look at superconductors
From sustainable energy to quantum computers: high-temperature superconductors have the potential to revolutionize today's technologies.

Read More: Superconductors News and Superconductors Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.