Effect of Disorder on the Temperature-Independent Magnetic Susceptibility of Se and Ge

Observations are reported of the room-temperature specific diamagnetic susceptibility of both the polycrystalline (${\chi }_c$) and amorphous (${\chi }_a$) forms of Se and Ge using a new type of rotating-sample magnetometer. Measurements performed on 99.9999% pure Se yielded a ratio $\frac{{\chi }_a}{{\chi }_c}=1.0\mathrm{}\pm 0.05$. For Ge a ratio $\frac{{\chi }_a}{{\chi }_c}=2.7\mathrm{}\pm 0.3$ was obtained. Although an enhanced diamagnetism has been observed in the disordered modification of serveral materials, the ratio for Ge is the largest yet reported. The amorphous Ge was prepared by evaporating a 3-$\mu$- thick film onto a Pyrex substrate at room temperature. The enhanced diamagnetism of the $a-\mathrm{G}\mathrm{e}$ was observed to be independent of annealing below crystallization.