Suppression of the impurity-induced local magnetism by the opening of a spin pseudogap in Ni-doped Sr${}_2$CuO${}_3$

Abstract

The $S=1/2$ antiferromagnetic Heisenberg spin chain compound Sr${}_2$CuO${}_3$ doped with $1\%$ and $2\%$ of Ni impurities has been studied by means of ${}^{63}$Cu nuclear magnetic resonance. A strong decrease of the spin-lattice relaxation rate $T_1^{-1}$ at low temperatures points toward a spin gap, while a stretching exponent $\lambda <1$ and a frequency dependence of $T_1^{-1}$ indicate that this spin gap varies spatially and should rather be characterized as a spin pseudogap. The magnitude of the spin pseudogap scales with doping level. Our results therefore evidence the finite-size character of this phenomenon. Moreover, an unusual narrowing of the low temperature NMR lines reveals the suppression of the impurity-induced staggered paramagnetic response with increasing doping level.

arXiv comment5 pages, 3 figures, 4 pages appendices

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Cited by in corpus (7)

• Heat transport of cuprate-based low-dimensional quantum magnets with strong exchange coupling
• Impurities in weakly coupled quantum spin chains Sr${}_2$CuO${}_3$ and SrCuO${}_2$
• The effect of different in-chain impurities on the magnetic properties of the spin chain compound SrCuO${}_2$ probed by NMR
• Spin pseudogap in the $S=\frac{1}{2}$ chain material Sr${}_2$CuO${}_3$ with impurities
• The dynamic structure factor in impurity-doped spin chains
• Effects of quantum impurity spins on the magnetic properties of zigzag and linear spin chains
• Monovacancy paramagnetism in neutron-irradiated graphite probed by ${}^{13}$C NMR