## "Are Polarization and Magnetization Really Bulk Properties?"
Are Polarization and Magnetization Really Bulk Properties? Raffaele Resta Dipartimento di Fisica, Università di Trieste, Italy Textbooks typically attempt microscopic definitions in terms of the dipole moment per cell: this is only correct for the spin contribution to magnetization M, but is incorrect for both polarization P and for the orbital contribution to M. The microscopic quantities well defined inside a polarized material are the microscopic charge and current densities: these trivially determine the dipole (electric and magnetic) of a finite sample, but the sample boundary yields an extensive contribution to such dipoles. Contrary to what textbooks pretend, the microscopic charge and current densities in the bulk of a sample do not determine the values of P and M. The problem has been solved in 1993 for P and in 2005-6 for M. In the latter case, there have been recent developments at the fundamental level[1]. In this talk I will outline the state of the art about P and M. [1] R. Bianco and R. Resta, ?Orbital Magnetization as a Local Property?, Phys. Rev. Lett. 110, 087202 (2013). |