Quadrupole spin-echo envelopes for Bi4Ge3O12 single crystals doped with the atoms of transition and rare-earth elements

摘要

The influence of a weak (below 50 Oe) constant magnetic field on a quadrupole spin-echo envelope was studied for an undoped single crystal Bi4Ge3O12, in which local magnetic fields on the order of 20-30 G were previously found, as well as for single Bi4Ge3O12 crystals doped with the atoms of transition and rare-earth elements. In all of these cases, the spin-echo envelopes were strongly influenced. A considerable increase in the nuclear spin-spin relaxation time T-2 was observed for the undoped sample upon the switching of weak external magnetic fields. For the doped samples, the spin-echo envelope decay became much slower already in the zero field. The external magnetic fields exhibited a markedly weaker influence on the spin-echo envelope for the doped samples.