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Durham University

Department of Physics

Staff profile

Publication details for Professor Tom Lancaster

Opherden, D., Nizar, N., Richardson, K., Monroe, J. C., Turnbull, M. M., Polson, M., Vela, S., Blackmore, W. J. A., Goddard, P. A., Singleton, J., Choi, E. S., Xiao, F., Williams, R. C., Lancaster, T., Pratt, F. L., Blundell, S. J., Skourski, Y., Uhlarz, M., Ponomaryov, A. N., Zvyagin, S. A., Wosnitza, J., Baenitz, M., Heinmaa, I., Stern, R., Kühne, H. & 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.

Author(s) from Durham

Abstract

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.