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arXiv · 0807.1506

Isotope effect in quasi-two-dimensional metal-organic antiferromagnets

P. A. Goddard·J. Singleton·C. Maitland·S. J. Blundell·T. Lancaster·P. J. Baker·R. D. McDonald·S. Cox·P. Sengupta·J. L. Manson·K. A. Funk·J. A. Schlueter
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Abstract

Although the isotope effect in superconducting materials is well-documented, changes in the magnetic properties of antiferromagnets due to isotopic substitution are seldom discussed and remain poorly understood. This is perhaps surprising given the possible link between the quasi-two-dimensional (Q2D) antiferromagnetic and superconducting phases of the layered cuprates. Here we report the experimental observation of shifts in the Néel temperature and critical magnetic fields ($ΔT_{\rm N}/T_{\rm N}\approx 4%$; $ΔB_{\rm c}/B_{\rm c}\approx 4%$) in a Q2D organic molecular antiferromagnets on substitution of hydrogen for deuterium. These compounds are characterized by strong hydrogen bonds through which the dominant superexchange is mediated. We evaluate how the in-plane and inter-plane exchange energies evolve as the hydrogens on different ligands are substituted, and suggest a possible mechanism for this effect in terms of the relative exchange efficiency of hydrogen and deuterium bonds.

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P. A. Goddard, J. Singleton, C. Maitland, S. J. Blundell, T. Lancaster, P. J. Baker, R. D. McDonald, S. Cox, P. Sengupta, J. L. Manson, K. A. Funk, J. A. Schlueter. 2008-07-11. Isotope effect in quasi-two-dimensional metal-organic antiferromagnets. https://doi.org/10.1103/physrevb.78.052408

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