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.

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 - Condensed Matter and Materials Physics
• 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
• Public URL: https://durham-repository.worktribe.com/output/1400627
• Related Public URLs: http://arxiv.org/abs/1505.08092