Antiferromagnetic order in the ladder compound SrCu{sub 2}O{sub 3}: Cu-NMR/NQR measurements

Abstract

We carried out the extensive Cu-nuclear magnetic and quadrupole resonance (NMR/NQR) experiments on the Zn(Ni)-doped ladder compound SrCu 2 O 3 (Sr123), Sr(Cu 1−x M x ) 2 O 3 (M=Zn and Ni) with x ≤ 0.02 and the Ladoped Sr123, Sr 1−x La x Cu 2 O 3 with x ≤ 0.03. A spin-correlation length ξ s /a (a: the lattice spacing between the Cu sites along the leg) of nonmagnetic impurity-induced staggered polarization (IISP) estimated from a quasi-one-dimensional (Q1D) IISP along the two legs in the 0.1−2 % Zn-doped Sr123 was found to be independent of temperature (T) and scaled to an mean impurity distance D AV with the relation of ξ s /a = 2.5 + 0.1D AV The ξ s /a's are much longer in x = 0.001 (ξ s /a ∼50) and 0.005 (ξ s /a ∼ 12) than an instantaneous spin-correlation length ξ 0 /a ∼ 3 − 8 in Sr123. The formula of Neel T, T N (WC-Q1D)=J exp(−D AV /(ξs/a)) (J = 2000 K) based on the weakly interladder-coupled (WC) Q1D model explains the experimental T N values quantitatively.