Friday, August 26 2005 15:25 Hrs (IST) - World Time -

Santa Cruz (US): In a theoretical breakthrough, an Indian physicist at the University of California at Santa Cruz (UCSC) and his student have discovered a new mechanism for metallic magnetism that plays an important role in superconductors and magnetic storage devices such as computer hard drives.

The paper by Sriram Shastry and Jan Haerter in today's (August 26, 2005) issue of the journal, Physical Review Letters, that explains 'kinetic antiferromagnetism' solves a problem that has stumped theoretical physicists for decades.

"It is a basic theory paper that predicts metallic antiferromagnetism in certain kinds of lattices such as sodium cobalt oxide," Shastry told PTI in an interview.

"Metallic magnetism is a real frontier field in theoretical physics and it has practical applications in materials science."

Shastry who left the Indian Institute of Science in Bangalore two years ago, to join UCSC, and his student were interested in the unusual magnetic behaviour of sodium cobalt oxide, a material first described in 1997 and intensively studied in recent years.

The material can be made with variable amounts of sodium ions sandwiched between layers of cobalt oxide. The cobalt atoms form a triangular lattice structure that gives rise to 'electronic frustration,' which refers to the inability of the electrons in the system to achieve a single state that minimizes their total energy.

Theoretical understanding of why 'frustrated' materials like the sodium cobalt oxide are antiferromagnetic has remained unsolved for the past 40 years. "This problem has been a tough nut to crack. We were able to make some progress and came up with a surprising result," Shastry said.