Disorder-induced Spin Gap in the Zigzag Spin-1/2 Chain Cuprate Sr_{0.9}Ca_{0.1}CuO_2

Abstract

We report a comparative study of 63Cu Nuclear Magnetic Resonance spin lattice relaxation rates, T_1^{-1}, on undoped SrCuO_2 and Ca doped Sr_{0.9}Ca_{0.1}CuO_2 spin chain compounds. A temperature independent T_1^{-1} is observed for SrCuO_2 as expected for an S=1/2 Heisenberg chain. Surprisingly, we observe an exponential decrease of T_1^{-1} for T < 90,K in the Ca-doped sample evidencing the opening of a spin gap. The data analysis within the J_1-J_2 Heisenberg model employing density-matrix renormalization group calculations suggests an impurity driven small alternation of the J_2-exchange coupling as a possible cause of the spin gap.

4 pages, 4 figures

References in corpus (1)

• Current spinon-holon description of the one-dimensional charge-transfer insulator SrCuO2: Angle-resolved photoemission measurements

Cited by in corpus (9)

• Spin Gap in the Single Spin-1/2 Chain Cuprate Sr${}_{1.9}$Ca${}_{0.1}$CuO${}_3$
• Finite-size effects in the quasi-one-dimensional quantum magnets Sr${}_2$CuO${}_3$, Sr${}_2$Cu${}_{0.99}$M${}_{0.01}$O${}_3$ (M = Ni, Zn), and SrCuO${}_2$
• Bond disorder and spinon heat transport in the $S=\frac{1}{2}$ Heisenberg spin chain compound Sr${}_2$CuO${}_3$: from clean to dirty limits
• Magnetic properties of S = 5/2 anisotropic triangular chain Bi3FeMo2O12
• Crossover of the high-energy spin fluctuations from collective triplons to localized magnetic excitations in doped Sr14-xCaxCu24O41 cuprate ladders
• 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
• Spin-$S$ impurities with XXZ anisotropy in a spin-1/2 Heisenberg chain