We have investigated spin dynamics of both the ladder and the chain sites in Sr14Cu24O41 by Cu-NMR and Cu-NQR. From the NMR shift, Kspin, and nuclear spin-lattice relaxation time, T1, the energy gaps in the spin excitation spectrum are confirmed to be Δ = 140 K for the chain site and Δ = 470 K for the ladder site for Sr14Cu24O41 . Doping effects on the spin gaps and electric field gradient at the Cu sites were also investigated by the substituting of Ca, Y and La for Sr. The spin gap of the ladder site decreases with increasing x for Sr14-xCaxCu24O41 and seems to collapse at around x = 13 for Ca substitution.
- Nuclear spin-lattice relaxation time
- Spin gap
- Spin ladder
ASJC Scopus subject areas
- Physics and Astronomy(all)