U.S. Naval Research Laboratory scientists have discovered opposite spin polarization in the Dirac surface state of bismuth selenide, a topological insulator, and the two-dimensional electron gas surface state of a common semiconductor known as indium arsenide.
The scientists detected spin polarization that was produced by an unpolarized bias current through the use of a ferromagnetic tunnel barrier contact, NRL said Thursday.
“Detecting this spin polarization directly as a voltage, and differentiating the contributions from these two fundamentally different systems, is key to understanding the basic properties of TI materials and interfacing them to electronic circuitry for future device applications,” said Connie Li, the study’s lead author.
The research team also used spin-dependent electrochemical potentials to create a model designed to obtain the sign of the spin voltage for surface states of topological insulator materials.
The study was published in the Nov. 16, 2016 issue of the journal Nature Communications.