title: Maxwell equation for coupled spin-charge wave propagation.
abstract: We show that the dissipationless spin current in the ground state of the Rashba model gives rise to a reactive coupling between the spin and charge propagation, which is formally identical to the coupling between the electric and the magnetic fields in the (2 + 1)-dimensional Maxwell equation. This analogy leads to a remarkable effect of fractionalization of spin packets (FSP) where a density packet can spontaneously split into two counterpropagation packets, each carrying the opposite spin. In a certain parameter regime, the coupled spin and charge wave propagates like a transverse "photon." We propose both optical and purely electronic experiments to detect the FSP effect.
authors.affiliation: Department of Physics, Stanford University, California 94305, USA.
authors.forename: B Andrei
authors.initials: BA
authors.lastname: Bernevig
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Yu
authors.forename: Shou-Cheng
authors.initials: SC
authors.lastname: Zhang