Magnetic Susceptibility of Amorphous Semiconductors

Previously observed paramagnetic contributions to the magnetic susceptibility of ${\mathrm{As}}_2$ ${\mathrm{S}}_3$ and ${\mathrm{As}}_2$ ${\mathrm{Se}}_3$ glasses are shown to be due to iron impurities. The density of singly occupied localized states is below 3×${10}^{16}$ per ${\mathrm{cm}}^3$ in ultrapure glasses. Careful measurements of the diamagnetic susceptibility of both the glassy and crystalline phases of several glass-forming semiconductors indicate that the difference in diamagnetism of the phases is small.