| This doesn't quite get to ELI5 but hopefully is understandable to an HN audience (please feel free to correct if I've gotten anything incorrect): "Topological" and "magnetic" are two separate concepts (see below). Phase just refers to "phase of matter" - it's used here because a material has different properties depending on the external environment (like heating a magnet beyond a certain point means it's no longer magnetic). Topological typically refers to a "topological band structure". If you know some band theory: a material can be classed as an insulator, conductor, or semiconductor based on its band gap. A topological material is "mostly" an insulator, but has a special set of conductive channels on the surface. Remember that an electron has this additional property of spin ("up" or "down"). The topological material is furthermore unique in that these conducting channels only conduct electrons with a particular spin. The channels are also "topologically protected", so they are immune to material imperfections and have dissipation-less conductance (kind of "superconducting" in laymen's terms, but this has a different specific meaning in physics). Normally these topological materials are not magnetic (the topological effect is closely related to magnetic ordering), but this paper shows evidence of both, and also demonstrates that the electronic properties can be modulated by applying external magnetic field. So combining all of this, an application of interest in computing is "spintronics", where electronics use spin current rather than charge current. Dissipation-less conductance means much more power efficient, and spin isn't volatile like charge (HDD vs RAM). Topological materials are also being explored as a promising hardware platform for quantum computing. |