15 May 2007

Budding physicists learn at an early age that electrical resistance opposes the flow of charge, and is an inherently positive quantity. But researchers from Turkey and Germany studying 2D electron gases at low temperatures in a semiconductor now claim to have witnessed "negative resistance". They say that the odd effect could be used to make tiny sources of terahertz radiation, which can normally only be produced in much larger devices such as synchrotrons (Phys. Rev. Lett. 98 186801).

10 July 1998

Two US scientists claim to have discovered a new electrical effect called negative resistance in carbon-composite materials. And when materials exhibiting negative resistance are combined with 'normal' materials, they appear to have zero resistance to electrical current, similar to superconducting materials. Moreover, this behaviour persists to room temperature, whereas "high-temperature" superconductors only lose their resistance below about 150K or -120 C. The results were presented at fifth International Conference on Composites Engineering in Las Vegas.

Full text: http://physicsweb.org/articles/news/2/7/4/1