Berlin 2008 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 2: Symposium: High Magnetic Field Phenomena in Low Dimensional Magnets

TT 2.2: Hauptvortrag

Montag, 25. Februar 2008, 10:00–10:30, H 0104

High Field NMR in Low Dimensional Quantum Antiferromagnets — •Claude Berthier¹, Hadrien Mayaffre², Martin Klanjšek¹, Steffen Krämer¹, and Mladen Horvatić¹ — ¹Grenoble High Magnetic Field Laboratory (GHMFL), CNRS, BP — ²Lab. de Spectrométrie Physique, UJF Grenoble I

We present high field NMR studies of the field induced magnetic ordering in a few quasi-1D quantum antiferromagnets. Cu₂(C₅H₁₂N₂)₂Cl₄ (Cu(Hp)Cl) has for long been considered as the archetype of a strong coupling spin-ladder system. We show that it can be well understood in the framework of a spin-ladder with a staggered Dzyaloshinskii-Moriya (DM) interaction on the rungs [1]. CuBr₄(C₅H₁₂N)₂ (BPCB) is made of regular spin-ladders (without DM interaction) weakly coupled together. Its phase diagram between the two quantum critical field H_c1 and H_c2 is fully dominated by the H dependence of the Luttinger liquid parameters of the ladders [2]. We also briefly report the NMR evidence for the existence of an unconventional quantum ground state in the 1/3 magnetization plateau in the frustrated diamond chain compound Cu₃(CO₃)₂(OH)₂ (azurite) [3].

[1] M. Clémancey et al., Phys. Rev. Lett. 97, 167204 (2006).

[2] M. Klanjšek, H. Mayaffre, et al., unpublished.

[3] S. Krämer et al., unpublished.