The discovery of the first 2D material that acts as a magnetic topological insulator in the absence of an external magnetic field has been claimed by physicists in South Korea and the US. The material is chromium triiodide and its magnetic properties were characterized by analysing spin oscillations that were induced by neutron scattering.

When atoms inside a 2D material are arranged in certain patterns, their constituent electrons can display a fascinating range of behaviours not usually seen in everyday materials. Within the 2D honeycomb lattice of graphene, for example, so-called “Dirac electrons” can move at relativistic speed and behave much like photons with zero mass.

Some materials can also have interesting properties related to topology. In 2D, topological insulators are a class of materials in which electrons flow freely along the edges of a sheet but cannot flow along the surface. This effect is dependent upon the spin of the electrons and as a result, 2D topological insulators are of great interest to physicists developing spintronic devices in which information is stored and processed using the spin states of electrons.

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