Change of perspective in the electronic landscape
Time and again, even simple materials take physicists by surprise. Researchers at the Max Planck Institute for Chemical Physics of Solids in Dresden have observed an electronic property in the metal bismuth which they expected only in significantly more complex materials. In bismuth, electrons behave differently to free electrons in simple metals: depending on the direction in which they move through the crystal, it is sometimes easier and sometimes more difficult for them to make headway, as their energy distribution depends on the perspective. This can be compared to a mountain range where a hiker must surmount many high peaks on one route, but encounters only very few peaks on a different one. Remaining with this analogy, other metals resemble more a plain that looks the same in all three directions. In bismuth, the energy mountain range contains three so-called valleys in which the electrons can collect. Surprisingly, the electrons...