A group of Japanese, German and UT physicists recently found magnetic properties in strontium ruthenate, which is likely to change what theorists believe about the behavior of superconductors.

UT physicist Ward Plummer Marleigh Gossan 8/23/00 Carolina Powers 8/23/00 researched the surface of strontium ruthenate with Rene Matzdorf, Carolina Powers 8/23/00 a Humbolt Fellow who left UT during the Spring 2000 Semester, as well as Yoshi Tokura and K

iyo Terakura, Carolina Powers 8/23/00 both from the University of Tokyo and the Joint Research Center for Atom Technologies in Tsukuba, Japan. Zhong Fang and Tsuyoshi Kimura Carolina Powers 8/23/00 from the research center also collaborated on the project

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According to Plummer, who also performed research at the Oak Ridge National Laboratory, the surface of the superconducting material becomes magnetic when a crystal is broken apart.

Superconductors of a high temperature, usually containing copper, conduct electricity with little resistance. In the past, it was assumed by scientists that superconductivity and magnetism could not coexist because a current created by a magnetic field wo

uld cancel out the magnetism. However, those assumptions were questioned with the research of strontium ruthenate, a compound of strontium, ruthenium and oxygen.

This development and this class of material totally challenges all the assumptions about condensed materials, Plummer said. The Ruthenium should not be magnetic under normal circumstance.

We found that the surface is structurally different from the bulk of the material.

The researchers had discovered that when the strontium ruthenate crystals were broken open and the temperature began to drop, the surface of the compound became increasingly magnetic.

This discovery could foreshadow the invention of a switch that could allow a superconductor, like strontium ruthenate, to be switched on and off with a magnetic field, Plummer said. However, he said he believes this might be a few years off.

I do not expect any great devices to come out in my scientific lifetime, Plummer said. At face value, this is an intellectual curiosity, but it is also a good test vehicle for theoretical scientists.

Jiandi Zhang, from Florida International University, and Ismail, Carolina Powers 8/23/00 yes, single word name from the Oak Ridge National Laboratory, were also co-investigators in the research. Nancy O’Reilly 8/23/00 cq