Single-Interface Casimir Torque
  It is shown that the quantum fluctuations of the electromagnetic field generally induce a torque at the interface of an anisotropic material with another anisotropic or isotropic material. It is proven that this torque depends on an interface zero-point energy determined by the dispersion of the interface (localized and extended) modes. Our theory demonstrates that the single-interface torque is essential to understand the Casimir physics of material systems with anisotropic elements and determines the equilibrium positions of the system. 
Tiago A. Morgado and M\'ario G. Silveirinha
cond-mat.mes-hall