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arXiv:1403.2890 · Physical Review B

Spin gap in the single spin- 12 chain cuprate Sr1.9 Ca0.1 CuO3

Franziska Hammerath, E. M. Brüning, Samuele Sanna, Yannic Utz, Neela Sekhar Beesetty, R. Saint-Martin, A. Revcolevschi, Christian Heß, Bernd Büchner, H.‐J. Grafe

Published May 16, 2014• 18 citations
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Abstract

We report $^{63}\mathrm{Cu}$ nuclear magnetic resonance and muon spin rotation measurements on the $S=1/2$ antiferromagnetic Heisenberg spin chain compound ${\mathrm{Sr}}_{1.9}$${\mathrm{Ca}}_{0.1}$${\mathrm{CuO}}_{3}$. An exponentially decreasing spin-lattice relaxation rate ${T}_{1}^{\ensuremath{-}1}$ indicates the opening of a spin gap. This behavior is very similar to what has been observed for the cognate zigzag spin chain compound ${\mathrm{Sr}}_{0.9}$${\mathrm{Ca}}_{0.1}$${\mathrm{CuO}}_{2}$, and it confirms that the occurrence of a spin gap upon Ca doping is independent of the interchain exchange coupling ${J}^{\ensuremath{'}}$. Our results therefore suggest that the appearance of a spin gap in an antiferromagnetic Heisenberg spin chain is induced by a local bond disorder of the intrachain exchange coupling $J$. A low-temperature upturn of ${T}_{1}^{\ensuremath{-}1}$ evidences growing magnetic correlations. However, zero-field muon spin rotation measurements down to 1.5 K confirm the absence of magnetic order in this compound, which is most likely suppressed by the opening of the spin gap.

DOI
10.1103/physrevb.89.184410

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