Opherden, D. and Nizar, N. and Richardson, K. and Monroe, J. C. and Turnbull, M. M. and Polson, M. and Vela, S. and Blackmore, W. J. A. and Goddard, P. A. and Singleton, J. and Choi, E. S. and Xiao, F. and Williams, R. C. and Lancaster, T. and Pratt, F. L. and Blundell, S. J. and Skourski, Y. and Uhlarz, M. and Ponomaryov, A. N. and Zvyagin, S. A. and Wosnitza, J. and Baenitz, M. and Heinmaa, I. and Stern, R. and Kühne, H. and Landee, C. P. (2020) 'Extremely well isolated two-dimensional spin-1/2 antiferromagnetic Heisenberg layers with a small exchange coupling in the molecular-based magnet CuPOF.', Physical review B., 102 (6). 064431.
We report on a comprehensive characterization of the newly synthesized Cu2+-based molecular magnet [Cu(pz)2 (2-HOpy)2](PF6 )2 (CuPOF), where pz = C4H4N2 and 2-HOpy = C5H4NHO. From a comparison of theoretical modeling to results of bulk magnetometry, specific heat, μ+SR, ESR, and NMR spectroscopy, this material is determined as an excellent realization of the two dimensional square-lattice S = 1 2 antiferromagnetic Heisenberg model with a moderate intraplane nearest-neighbor exchange coupling of J/kB = 6.80(5) K, and an extremely small interlayer interaction of about 1 mK. At zero field, the bulk magnetometry reveals a temperature-driven crossover of spin correlations from isotropic to XY type, caused by the presence of a weak intrinsic easy-plane anisotropy. A transition to long-range order, driven by the low-temperature XY anisotropy under the influence of the interlayer coupling, occurs at TN = 1.38(2) K, as revealed by μ+SR. In applied magnetic fields, our 1H-NMR data reveal a strong increase of the magnetic anisotropy, manifested by a pronounced enhancement of the transition temperature to commensurate long-range order at TN = 2.8 K and 7 T.
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|Publisher Web site:||https://doi.org/10.1103/PhysRevB.102.064431|
|Publisher statement:||Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.|
|Date accepted:||27 July 2020|
|Date deposited:||01 September 2020|
|Date of first online publication:||28 August 2020|
|Date first made open access:||01 September 2020|
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