A theory in the electric quadrupole-magnetic dipole approximation of birefringences in antiferromagnetic crystals

Abstract

While the magnetoelectric tensor correctly describes the magnetization density induced in a magnetic crystal by a uniform electric field, it is insufficient for explaining certain effects induced in such crystals by an electromagnetic field, for instance gyrotropic birefringence. To account for these effects the theory should include higher multipole contributions in a consistent way. In this paper a theory is presented in the electric quadrupole-magnetic dipole approximation of various birefringences in non-absorbing antiferromagnetic crystals of the uniaxial and cubic systems. As confirmation of the consistent inclusion of multipole terms, the expressions for the birefringences are found to be translationally invariant.

Key Words:

• Birefringence in antijerromagnetics
• gyrotropic birefringence.