The EPR and NQR in layered crystal of GaSe: Gd

The influence of the polytypical structure of GaSe on the shape of the EPR spectra of the gadolinium impurity in the Gd3+ state has been investigated. It is shown that in a layered crystal at impurity concentration of about 1018 cm-3 at least three types of paramagnetic centers appear. The presence of nonequivalent positions of the Gd3+ ion is explained by the presence of polytypic modifications in GaSe. It was revealed that the introduction of a paramagnetic impurity into the crystal significantly expands the NQR spectrum.