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arXiv · 1612.05217

Experimental Approach to the Thermodynamics of the Pure Two-Dimensional Spin-1/2 Triangular Lattice Antiferromagnet in Ba8CoNb6O24

Y. Cui·J. Dai·P. Zhou·P. S. Wang·T. R. Li·W. H. Song·L. Ma·Z. Zhang·S. Y. Li·G. M. Luke·B. Normand·T. Xiang·W. Yu
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Abstract

Frustrated quantum magnets pose well-defined questions concerning quantum fluctuation effects and the nature of the many-body wavefunction, which challenge theory, numerics, experiment and materials synthesis. The S = 1/2 triangular-lattice antiferromagnet (TLAF) presents a case where classical order is strongly suppressed by quantum fluctuations, leading to extensive renormalization of physical properties at all energy scales. However, purely two-dimensional (2D) models are difficult to realise in the 3D world and their physics is controlled by the Mermin-Wagner theorem, which describes the dominant effects of additional thermal fluctuations. Here we report the magnetic properties Ba8CoNb6O24, whose Co2+ions have an effective spin 1/2 and construct a regular TLAF with very large interlayer spacing. We find no magnetic ordering down to 0.028 K, strong low-energy spin fluctuations in qualitative agreement with theoretical analysis and a diverging correlation length, all indicating a Mermin-Wagner trend towards zero-temperature ordering in this ideal 2D system.

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Y. Cui, J. Dai, P. Zhou, P. S. Wang, T. R. Li, W. H. Song, L. Ma, Z. Zhang, S. Y. Li, G. M. Luke, B. Normand, T. Xiang, W. Yu. 2016-12-15. Experimental Approach to the Thermodynamics of the Pure Two-Dimensional Spin-1/2 Triangular Lattice Antiferromagnet in Ba8CoNb6O24. https://arxiv.org/abs/1612.05217

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