Researchers at Chalmers University of Technology have for the first time reported the electrical detection of spin current on topological insulator surfaces at room temperature by employing a ferromagnetic detector. The findings have been published in the journal Nano Letters.
Solid-state materials were conventionally divided into three different classes such as conductors, semiconductors and insulators. Recently, a new class of materials has been proposed and realized, called "topological insulators", where both the insulating and conducting properties can co-exist in the same material.
Topological insulators are insulators inside the bulk, but are conducting on their surfaces with less resistance than the conventional materials. This is possible due to their uniquely strong interaction between electrons' spin and orbital angular momentum with their time reversal symmetry. The interaction is so strong that the spin angular momentum of the electrons is locked perpendicular to their momentum, and generates a spontaneous spin polarized current on the surfaces of topological insulators by applying an electric field.
These spin polarized conducting electrons on the surface have no mass and are extremely robust against most perturbations from defects or impurities, and can enable the propagation of dissipationless spin currents.
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