Theory of the Magnetic Susceptibility of Tetrahedral Semiconductors

The magnetic susceptibility of an intrinsic tetrahedrally coordinated semiconductor is calculated using a tight-binding basis and approximations appropriate to the bond-orbital model. The susceptibility associated with the valence electrons is found to separate into a diamagnetic Langevin component and a paramagnetic Van Vleck component, both of which are found to be proportional to the square of the bond length, and nearly cancel in the homopolar semiconductors. The Langevin term is found to be approximately independent of polarity while the paramagnetic component varies with polarity, ${\alpha }_p$, as ${(1-{{\alpha }_p}^2)}^{\frac{3}{2}}$.