Spin vector potential and spin Aharonov-Bohm effect.

The Aharonov-Bohm (AB) effect is an important discovery of quantum theory. It serves as a surprising quantum phenomenon in which an electrically charged particle can be affected by an electromagnetic potential, despite being confined to a region in which both the magnetic field and electric field are zero. This fact gives the electromagnetic potentials greater significance in quantum physics than in classical physics. The original AB effect belongs to an "electromagnetic type". A certain vector potential is crucial for building a certain type of AB effect. In this work, we focus on the "spin", which is an intrinsic property of microscopic particles that has been widely accepted nowadays. First, we propose the hypothesis of spin vector potential by considering a particle with a spin operator. Second, to verify the existence of such a spin vector potential, we present a gedanken double-slit interference experiment (i.e., the spin AB effect), which is possible to be observed in the lab. Third, we apply the spin vector potential to naturally explain why there were the Dzyaloshinsky-Moriya-type interaction and the dipole-dipole interaction between spins, and also predict a new type of spin-orbital interaction.