Nuclear magnetic resonances have been observed for the more abundant nuclear species in the semi-conductors InSb and GaSb. Broad lines have been observed and explained by a nuclear spin exchange mechanism where the interaction between the nuclei is of the form $E_{\mathrm{ij}}=A_{\mathrm{ij}}{\mathrm{I}}_i·{\mathrm{I}}_j$. The exchange coupling involves the hyperfine interaction between nuclear spins and electron spins. Therefore it is very sensitive to the electron energy states in both valence and conduction bands. It is particularly sensitive to the energy surfaces far from the Fermi level and provides information about the band structure of these normally inaccessible regions.

• Received 17 May 1955

DOI:https://doi.org/10.1103/PhysRev.100.692