Physicists have discovered that ultra-thin flakes of bismuth exhibit mysterious magnetic properties, which could enable this soft, shiny metal to become an excellent material for creating more environmentally friendly electronics. The study was published in the journal Physical Review Letters, reports New Scientist.
Researchers suspected that very thin bismuth flakes might possess unusual physical properties, similar to other ultra-thin materials like graphene, which is made from carbon. However, due to bismuth being such a soft metal, it has been challenging to create flakes thin enough to reveal these unusual properties.
Recently, scientists developed a new technique for this, likening it to using a cheese grater. This allowed physicists to produce bismuth flakes just 68 nanometers thick, which is less than one thousandth the thickness of a sheet of paper. The researchers then subjected these flakes to various temperatures, ranging from nearly absolute zero to room temperature, and magnetic fields that are tens of thousands of times stronger than those of refrigerator magnets.
Under these conditions, bismuth consistently displayed a unique electromagnetic behavior. Specifically, whenever physicists connected wires to it, a type of electric current known as the anomalous Hall effect always emerged.
As a result, the researchers obtained findings that greatly surprised them, as the known properties of bismuth suggest it should not exhibit the anomalous Hall effect at all.
According to the physicists, since this effect manifests even at room temperature, ultra-thin bismuth could be useful for developing more eco-friendly electronic devices. The reason is that bismuth is less toxic than many similar materials used in electronics manufacturing.
The physicists were deeply astonished that the anomalous Hall effect persists even when bismuth is exposed to extremely strong magnetic fields. Even very high temperatures had no impact on this phenomenon.
Currently, physicists do not have any explanation for this, although there are some hypotheses. It is possible that the arrangement of bismuth's atoms restricts the energy and movement of their electrons according to a set of mathematical rules known as topology.