Magnetic ground state of the two isostructual polymeric quantum magnets [Cu(HF2)(pyrazine)2]SbF6 and [Co(HF2)(pyrazine)2]SbF6 investigated with neutron powder diffraction

Brambleby, J.; Goddard, P.A.; Johnson, R.D.; Liu, J.; Lancaster, T.; Manuel, P.; Baker, P.J.; Singleton, J.; Schwalbe, S.G.; Spurgeon, P.M.; Tran, H.E.; Peterson, P.K.; Corbey, J.F.; Manson, J.L.

doi:10.1103/physrevb.92.134406

Magnetic ground state of the two isostructual polymeric quantum magnets [Cu(HF2)(pyrazine)2]SbF6 and [Co(HF2)(pyrazine)2]SbF6 investigated with neutron powder diffraction

Brambleby, J.; Goddard, P.A.; Johnson, R.D.; Liu, J.; Lancaster, T.; Manuel, P.; Baker, P.J.; Singleton, J.; Schwalbe, S.G.; Spurgeon, P.M.; Tran, H.E.; Peterson, P.K.; Corbey, J.F.; Manson, J.L.

Authors

J. Brambleby

P.A. Goddard

R.D. Johnson

J. Liu

Professor Tom Lancaster tom.lancaster@durham.ac.uk
Professor

P. Manuel

P.J. Baker

J. Singleton

S.G. Schwalbe

P.M. Spurgeon

H.E. Tran

P.K. Peterson

J.F. Corbey

J.L. Manson

Abstract

The magnetic ground state of two isostructural coordination polymers, (i) the quasi-two-dimensional S=1/2 square-lattice antiferromagnet [Cu(HF2)(pyrazine)2]SbF6 and (ii) a related compound [Co(HF2)(pyrazine)2]SbF6, was examined with neutron powder diffraction measurements. We find that the ordered moments of the Heisenberg S=1/2 Cu(II) ions in [Cu(HF2)(pyrazine)2]SbF6 are 0.6(1)μb, while the ordered moments for the Co(II) ions in [Co(HF2)(pyrazine)2]SbF6 are 3.02(6)μb. For Cu(II), this reduced moment indicates the presence of quantum fluctuations below the ordering temperature. We show from heat capacity and electron spin resonance measurements that due to the crystal electric field splitting of the S=3/2 Co(II) ions in [Co(HF2)(pyrazine)2]SbF6, this isostructual polymer also behaves as an effective spin-half magnet at low temperatures. The Co moments in [Co(HF2)(pyrazine)2]SbF6 show strong easy-axis anisotropy, neutron diffraction data, which do not support the presence of quantum fluctuations in the ground state, and heat capacity data, which are consistent with 2D or close to 3D spatial exchange anisotropy.

Citation

Brambleby, J., Goddard, P., Johnson, R., Liu, J., Lancaster, T., Manuel, P., …Manson, J. (2015). Magnetic ground state of the two isostructual polymeric quantum magnets [Cu(HF2)(pyrazine)2]SbF6 and [Co(HF2)(pyrazine)2]SbF6 investigated with neutron powder diffraction. Physical review B, 92(13), Article 134406. https://doi.org/10.1103/physrevb.92.134406

Journal Article Type	Article
Acceptance Date	Sep 4, 2014
Online Publication Date	Oct 7, 2015
Publication Date	Oct 7, 2015
Deposit Date	Oct 14, 2015
Publicly Available Date	Nov 12, 2015
Journal	Physical Review B
Print ISSN	1098-0121
Electronic ISSN	1550-235X
Publisher	American Physical Society
Peer Reviewed	Peer Reviewed
Volume	92
Issue	13
Article Number	134406
DOI	https://doi.org/10.1103/physrevb.92.134406
Related Public URLs	http://arxiv.org/abs/1505.08092

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