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NMR and LDA evidence for spiral magnetic order in the chain cuprate LiCu2O2

A. A Gippius·E. N. Morozova·A. S. Moskvin·A. V. Zalessky·A. A. Bush·M. Baenitz·H. Rosner·S. -L. Drechsler
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Abstract

We report on {6,7}Li nuclear magnetic resonance measurements of the spin-chain compound LiCu2O2 in the paramagnetic and magnetically ordered states. Below T about 24 K the NMR lineshape presents a clear signature of incommensurate (IC) static modulation of the local magnetic field consistent with an IC spiral modulation of the magnetic moments. {7}Li NMR reveals strong phason-like dynamical fluctuations extending well below 24 K. We hypothesize that a series of phase transitions at 24.2, 22.5, and 9 K reflects a "Devil's staircase" type behavior generic for IC systems. LDA based calculations of exchange integrals reveal a large in-chain frustration leading to a magnetical spiral.

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A. A Gippius, E. N. Morozova, A. S. Moskvin, A. V. Zalessky, A. A. Bush, M. Baenitz, H. Rosner, S. -L. Drechsler. 2003-12-30. NMR and LDA evidence for spiral magnetic order in the chain cuprate LiCu2O2. https://doi.org/10.1103/physrevb.70.020406

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