Nickel gallium sulfide (NiGa₂S₄) may behave as a highly unusual "liquid" magnetic material at near absolute zero, according to Japanese and US researchers. The new material was synthesized by Satoru Nakatsuji, Yusuke Nambu, Hiroshi Tonomura, Osamu Sakai, Hirokazu Tsunetsugu, and Yoshiteru Maeno at Kyoto University, Japan, and its properties revealed in collaboration with Seth Jonas and Collin Broholm of Johns Hopkins University, Baltimore, Maryland, and Yiming Qiu of the National Institute of Standards and Technology and the University of Maryland.

A "liquid" magnetic state occurs when magnetic spins fluctuate in a disorderly, fluid-like arrangement that does not produce an overall magnetic force. Theoreticians first proposed this state 30 years ago and researchers now believe it could have relevance to explaining the similarly fluid way that electrons flow without resistance in superconductors. The current team has now found that the triangular arrangement of their material's atoms appears to prevent alignment of magnetic "spins," the characteristic of electrons that produces magnetism.

Material exist in a lower energy state than normal when their electron spins are aligned, but in nickel gallium sulfide the system is frustrated by the triangular nature of the crystal structure. "An ordered pattern of spins generally uses less energy," says JHU's Collin Broholm, "but the triangular crystal structure prevents this from happening in this material."

"The motivation for our research is to explore the qualitatively different phases of matter that may be possible when many spins interact," Broholm told Reactive Reports, "Such research impacts many areas of science and may lead to materials where quantum physics at atomic length scales produces unusual and useful properties at macroscopic length scales."

Science, 2005, 309, 1697-1700; http://dx.doi.org/10.1126/science.1114727
Frustrated magnets - http://www.sciencebase.com/nov02_iss.html