U prof’s research may hold energy answers

Physics professor Martin Greven has discovered a new use of a type of magnetic wave, which may contribute to superconductivity.


A University of Minnesota researcher is leading an international team that has shed new light on one of the most studied topics in history âÄî superconductivity. The research could potentially aid technology that could help solve the worldâÄôs energy crisis.

Physics professor Martin Greven has discovered a new use of a type of magnetic wave, previously overlooked by physicists, which may contribute to superconductivity. The magnetic wave, unique because of its use of oxygen atoms, may one day explain the marvel of superconductivity.

Superconductivity, discovered in 1911, is the phenomenon that negatively charged electrons in superconductors bond with each other âÄî against the basic principal that opposite charges attract âÄî resulting in a material that has an electrical resistance of zero.

A material that can conduct electricity with zero resistance is important because it could potentially transmit electricity to homes without losing energy to heat in the process, something that cannot be practically applied to current technology.

Copper wires are currently used to transmit electricity, but up to 10 percent of the electricity transported over them is lost to heat due to resistance. The new wires would make use of complex copper-oxide material that would allow the wires to be superconductive, Greven said.

While the superconducting wires Greven is researching must be cooled down by liquid nitrogen, a relatively inexpensive coolant, the ultimate goal among superconductive researchers is to create a superconductor that can function at room temperature.

“On one hand, we have copper, a simple metal thatâÄôs fully understood from a physics point of view, and on the other hand, we have these copper-oxide superconductors that are still giving us headaches,” Greven said.

“We are still rather clueless on how it is possible that these materials have these properties [of superconductivity] in the first place,” Greven said.

The copper-oxide is present in special crystals that are grown at the University. The crystals, which can weigh up to 2 grams, are formed in furnaces that heat up to 1,000 degrees Celsius âÄî melting everything âÄî before slowly descending in temperature to form the crystal.

The University currently has one of the countryâÄôs largest crystal growth labs, said Guichuan Yu, a post-doctorate research associate who has been working on the project with Greven. Yu and Greven are able to grow up to seven crystals at the same time. Some of the crystals formed at the University are sent around the world for research by other institutions trying to answer the same question of how superconductivity works.

“We donâÄôt have anyone else that grows crystal like the way Greven does,” said Ron Poling, head of the School of Physics and Astronomy.

The superconductive wires are formed by evaporating the copper-oxide crystals into the material used to form the wires.

Each crystal takes about four days to grow, Yu said.

Greven and his international team âÄî with researchers from China, France and Germany âÄî bombarded the crystals with neutrons in order to learn more about the magnetic wave that they believe is responsible for forming the bond between electrons.

This week, Greven and Yu will travel to France for a month, where they will work alongside other researchers in the same field.

Last month, South Korea ordered 1,864 miles of the superconductive wires, approximately the same distance between Liverpool and New York City.

“In addition to teaching us really fundamental things about physics, there are future technological applications,” Poling said. “High-temperature superconductors are starting to become commercialized, and by having a strong research program in the area, [the University] becomes part of that picture.”