Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 101: Correlated Electrons: Other Materials
TT 101.7: Vortrag
Donnerstag, 15. März 2018, 17:15–17:30, HFT-FT 101
Doping and magnetic field induced spin gaps in spin chains explored by NMR — •Hans-Joachim Grafe1, Yannic Utz1, Franziska Hammerath1,2, Lena Spillecke1, Margarita Iakovleva1, Evgeniya Vavilova1, Vladislav Kataev1, Tobias Ritschel2, Jochen Geck2, Chritian Hess1, Livio Hozoi1, Satoshi Nishimoto1, Stefan-Ludwig Drechsler1, and Bernd Büchner1,2 — 1IFW Dresden, Helmholtzstraße 20, 01069 Dresden, Germany — 2Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062 Dresden, Germany
We present NMR measurements on the Heisenberg spin chain SrCuO2 doped with Pd and Ni impurities [1], and on the frustrated edge-sharing S=1/2 chain LiCuSbO4 [2]. In SrCuO2, the dopants cut the chains into segments which leads to strongly decaying spin lattice relaxation rates T1−1 at low temperatures, indicating the opening of a spin gap. Thereby, it turned out that Ni is in a S=0 state instead of a S=1 state, which has been confirmed by x-ray absorption spectroscopy and quantum chemistry calculations. In LiCuSbO4, we observe a strongly field dependent spin lattice relaxation rate at low temperatures: at magnetic fields below 13T, T1−1 is dominated by a power-law increase, whereas above 13T, we observe a field induced spin gap-like decrease of T1−1. The former behavior is ascribed to diverging longitudinal spin correlations typical for a multipolar spin density wave liquid, whereas the latter is due to gapped transverse spin correlations characteristic for a spin-nematic liquid.
Y. Utz et al., Phys. Rev. B 96, 115135 (2017)
H.-J. Grafe et al., Scientific Reports 7, 6720 (2017)