Examining the topological material samarium hexaboride, scientists discover seemingly contradictory properties and an exciting, new mystery for physicists.
First, some background:
An insulator is a material that does not conduct electricity: its resistance to electrical flow increases as temperature decreases. Metals, however, become magnetic at low temperatures when subjected to an intense magnetic field.
What did scientists discover?
Researchers have found that the topological material, samarium hexaboride, behaves like an insulator and a metal … and its magnetic quantum oscillations (the size of the electron’s orbit in the material in response to an intense applied magnetic field) are more than five times too big to be explained by any known theory.
Why is this important?
Samarium hexaboride is apparently both an insulator and a metal … which is a bit like saying something is white and black at the same time. Because we understand simple insulators and metals extremely well, the only possible explanation is that the billions of electrons in samarium hexaboride have found a way to work collectively in some new and surprising way. They exhibit a new, emerging behavior that is neither — or perhaps both — insulator and metal, a strange hybrid that shows properties of each and new, unexpected behaviors never before seen.
Why did the research need high fields?
High magnetic fields amplify the quantum oscillations exponentially, enabling researchers to get the best possible understanding of new metallic behaviors or, in this case, to reveal a deep new mystery that remains unexplained.
Where was this work published?
Science 17 Jul 2015:
Vol. 349, Issue 6245, pp. 287-290