Dynamics and distribution of doped holes in the Cu0_2 plane of slightly doped antiferromagnetic YBa_2(Cu_(1-z)Li_z)_3O_(6+x) (x < 0.1) studied by Cu(1) NQR

摘要

Incidence of doped holes .in the Cu0_2 plane on the AF state was studied by Cu(1) nuclear quadrupole resonance (NQR) in slightly doped YBa_2(Cu_(1-z)Li_z)_30_(6+x) compounds. Inhomogeneous distribution of doped holes in the plane was detected in the low temperature measurements of transverse (1/T_2) and longitudinal (1/T_1) relaxation rates. We establish that at lower T the holes motion slows down and we estimate that the holes localize finally in restricted regions ～3 lattice constants) in the Coulomb potential of the Li~+ ions. Also we compared the hole behavior in slightly doped YBa_2(Cu_(1-z)Li_z)_30_(6+x). samples with that in slightly doped Yi_(1-y)Ca_yBa_2Cu_30_6. A stronger trapping potential of the in-plane Li~+ impurities was concluded as compared to slightly doped Yi_(1-y)Ca_yBa_2Cu_30_6 compound with out-of-plane Ca~(2+) impurities.