Scientists describe the quirky behavior of one such magnetic topological insulator. The new article includes experimental evidence that intrinsic magnetism in the bulk of manganese bismuth telluride (MnBi2Te4) also extends to the electrons on its electrically conductive surface. Such materials could be just right for making qubits, but this one doesn’t obey the rules.

«Exploring the complexity of topological materials — along with other intriguing emergent phenomena such as magnetism and superconductivity — is one of the most exciting and challenging areas of focus for the materials science community at the U.S. Department of Energy’s Brookhaven National Laboratory,» said Peter Johnson, a senior physicist in the Condensed Matter Physics & Materials Science Division at Brookhaven. «We’re trying to understand these topological insulators because they have lots of potential applications, particularly in quantum information science, an important new area for the division.»

For example, materials with this split insulator/conductor personality exhibit a separation in the energy signatures of their surface electrons with opposite «spin.» This quantum property could potentially be harnessed in «spintronic» devices for encoding and transporting information. Going one step further, coupling these electrons with magnetism can lead to novel and exciting phenomena.

«When you have magnetism near the surface you can have these other exotic states of matter that arise from the coupling of the topological insulator with the magnetism,» said Dan Nevola, a postdoctoral fellow working with Johnson. «If we can find topological insulators with their own intrinsic magnetism, we should be able to efficiently transport electrons of a particular spin in a particular direction.»

In a new study just published and highlighted as an Editor’s Suggestion in Physical Review Letters, Nevola, Johnson, and their coauthors describe the quirky behavior of one such magnetic topological insulator. The paper includes experimental evidence that intrinsic magnetism in the bulk of manganese bismuth telluride (MnBi2Te4) also extends to the electrons on its electrically conductive surface. Previous studies had been inconclusive as to whether or not the surface magnetism existed.

But when the physicists measured the surface electrons’ sensitivity to magnetism, only one of two observed electronic states behaved as expected. Another surface state, which was expected to have a larger response, acted as if the magnetism wasn’t there.

Story Source: Materials provided by DOE/Brookhaven National Laboratory. Note: Content may be edited for style and length.