New findings from three teams may solve a 40-year-old mystery regarding the odd electrical behavior of samarium hexaboride, which may be a topological insulator in its bulk form.

A compound whose odd electrical behavior has puzzled physicists for decades could turn out to be a boon for quantum physics and electronic-device makers.

When theorists proposed in 2005 that it should be possible to find materials that conduct electricity at the surface while the rest of the sample behaves as an insulator, physicists were intrigued. They wanted to study the quantum effects that should emerge in such materials, and to explore applications in low-power electronics and quantum computing. But topological insulators, as the materials were called, proved fiendishly difficult to make. Some researchers have slaved to produce thin films using complex techniques that are unlikely ever to scale up to the levels needed for industrial purposes. Others have contented themselves with compounds that approximate topological insulators but still have a degree of internal conductivity.

Now, three papers suggest that samarium hexaboride, a poorly understood compound that was first found to gain conducting properties at very low temperatures in 1969 by researchers at Bell Labs in New Jersey, may in fact be a topological insulator in its bulk form.

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