Enigmatic materials that conduct electricity at only their surfaces, known as topological insulators, could be used to measure the fine structure constant, α - one of three factors that determine the speed of light. Joseph Maciejko at Stanford University in California and his team propose measuring α by observing the quantized magnetoelectric effect (QME) - a predicted phenomenon in which an electric field induces magnetization in discrete quantum steps. The proposed experiment would use a layer of a topological insulator on top of a layer of ordinary insulator, all sitting in an external magnetic field.
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