Disorder-induced Spin Gap in the Zigzag Spin-1/2 Chain Cuprate Sr_{0.9}Ca_{0.1}CuO_2
| Autor: | Hammerath, F., Nishimoto, S., Grafe, H. -J., Wolter, A. U. B., Kataev, V., Ribeiro, P., Hess, C., Drechsler, S. -L., Buechner, B. |
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| Rok vydání: | 2011 |
| Předmět: | |
| Zdroj: | Phys. Rev. Lett. 107, 017203 (2011) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevLett.107.017203 |
| Popis: | 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. Comment: 4 pages, 4 figures |
| Databáze: | arXiv |
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