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Étude RMN du système de spins quantiques CuHpCl

Abstract : We present an NMR study of magnetic properties of Cu2(C5H12N2)2Cl4 (CuHpCl). This system of quantum spins ½ has been considered for a long time as an experimental realization of a spin ladder system. Its phase diagram under magnetic field is very rich, in particular a spin liquid ground state in zero field and two quantum phase transitions at Hc1=7.5 Tesla and Hc2 = 13 Tesla. The first goal of this study was a clarification of some specific parts of the phase diagram, in particular the low temperature regime between Hc1 and Hc2, where tridimensional magnetic order sets in. Through the study of a compound deuterated on specific hydrogen bonds, we observed the commensurate nature of this ordered phase. The second-order phase transition was studied as a function of H and T. The main result of this study highlights the apparition at low temperature of a staggered transverse magnetisation, due to antisymetric magnetic interactions, like observed in other spin liquid compounds like NENP or SrCu2(BO3)2. This « anomalous » magnetisation appears for fieds Hc1 and persist for H> Hc2. CuHpCl is the first compound where the coexistence of a staggered magnetisation with 3D magnetic order can be observed. We also observed by torque magnetometry anomalous features due to this staggered magnetisation. Last, in order to understand the magnetic exchange pathways in CuHpCl, we also undertook NMR and torque measurements of methylated variants of CuHpCl.
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https://tel.archives-ouvertes.fr/tel-00006399
Contributor : Martin Clémancey <>
Submitted on : Wednesday, July 7, 2004 - 11:01:26 AM
Last modification on : Tuesday, September 11, 2018 - 11:00:02 AM
Long-term archiving on: : Friday, April 2, 2010 - 8:56:47 PM

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  • HAL Id : tel-00006399, version 1

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Martin Clémancey. Étude RMN du système de spins quantiques CuHpCl. Matière Condensée [cond-mat]. Université Joseph-Fourier - Grenoble I, 2004. Français. ⟨tel-00006399⟩

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