Topological quantum field effect transistor

A structure comprising:

• a gate electrode,
• a dielectric layer, and
• a planar layer of a topological material being separated from the gate electrode by at least the dielectric layer, and having a contact interface with the dielectric layer to generate an electric field-controlled Rashba spin-orbit interaction on application of an electric field thereto,
• wherein the topological material exhibits a topological phase transition between a trivial state and a non-trivial state at a critical electric field strength on application of the electric field,
• wherein the gate electrode is configured to apply the electric field across the planar layer in a direction perpendicular to a plane of the planar layer;
• and
• wherein the topological material exhibits a change in bandgap potential having a spin contribution of magnitude ΔR=αREz and a non-spin contribution of magnitude ΔV=αvEz;
• where:
• ΔR is the spin-dependent contribution to the change in bandgap;
• αR is a proportionality constant representing the spin-dependent contribution to the change in bandgap;
• ΔV is the non-spin-dependent contribution to the change in bandgap;
• and
• αv is a proportionality constant representing the non-spin-dependent contribution to the change in bandgap;
• Ez is the electric field strength;
• and
• wherein αR>αv/3.