Renormalization of spin-rotation coupling and Barnett fields

Ieda, Junichi   ; Matsuo, Mamoru; Maekawa, Sadamichi

There are two physical mechanisms that combine magnetism and mechanical rotation. One is the Einstein de Haas (EdH) effect, the other the Barnett effect. The EdH effect has been shown to be promising in application to nanomechanics and spintronics. The reciprocal of the EdH effect, the Barnett effect implies an emergent magnetic field, i.e., the Barnett field. Both the effects essentially originate from the spin-rotation coupling. We show the enhancement of the spin-rotation coupling due to the interband mixing. The Bloch wave functions in the presence of mechanical rotation are constructed with the generalized crystal momentum that includes a gauge potential originating from the rotation. Using the Kane model, the renormalized spin-rotation coupling is explicitly derived. As a result of the renormalization, the Barnett field, the mechanical torque on an electron spin, and the spin current generation due to elastic deformation will be strongly enhanced. We also discuss recent experimental results on observation of the Barnett field in solids by nuclear magnetic resonance and its implication in future spin mechanics applications.