Gravitomagnetic Barnett Effect
  Using the linearized theory of general relativity, the gravitomagnetic analogue of the Barnett effect is derived. Further theoretical and experimental investigation is recommended, due to the expected macroscopic values of the gravitomagnetic field involved in this effect, and to the constraints which would appear on quantum theories of gravity, currently under development, in case of non detection of the predicted phenomena. 
C.J. de Matos, M. Tajmar