Separation of quadrupole and magnetic mechanismsof 209Bi nuclear spin–lattice relaxation in Bi4Ge3O12

Abstract

AbstractBi4Ge3O12 belongs to the class of complex Bi‐oxides (α‐Bi2O3, Bi3O4Br) which exhibits unusual magnetic properties. Local magnetic fields of about 30 G were revealed in the Bi4Ge3O12 single crystal by 209Bi NQR experiments. In the present paper the nuclear spin–lattice relaxation was studied in the Bi4Ge3O12 single crystal by 209Bi NQR spin–echo technique. The experimental relaxation curves were described by the single effective spin–lattice relaxation time T1. The temperature dependence of 1/T1 was close to Tn law with n = 2.4 – 2.7. The nuclear spin–lattice relaxation in the multi‐level system was theoretically calculated for the case of single‐axial crystalline electric field. Both quadrupole and magnetic mechanisms of relaxation were taken into account. We conclude that the magnetic mechanism contributes noticeably to the spin–lattice relaxation in Bi4Ge3O12 at T ≤ 50 K.