Chemical control of magnetism in <i>S</i> = 1 quantum materials: new twists on a seemingly old theme
· Invited
Abstract
We aim to control the spatial exchange and single-ion anisotropies (D) in bespoke S = 1 Ni(II) quantum magnets. Early work led to [Ni(HF2)(pyz)2]SbF6 (pyz = pyrazine) which contains Ni-FHF-Ni chains (JFHF) cross-linked by Ni-pyz-Ni segments (Jpyz) to form a tetragonal network [1]. The material undergoes XY-AFM order below TN = 12.2 K with collinear Ni(II) moments confined to the [Ni(pyz)2]2+ plane. High-field M(H) and inelastic neutron scattering (INS) revealed D ≈ JFHF >> Jpyz. In the related square lattices [2,3], NiX2(pyz)2 (X = F, Cl, Br, I, NCS), the electronegativity of X dictates the Ni(II) spin direction with XY- and Ising-like ground-states observed for X = F, Cl and X = Br, I, NCS, respectively. We used INS to determine Jpyz and J⊥. Chemical substitution of pyz for pyrimidine (pym) affords unusual topologies and enhanced magnetic interactions along Ni-pym-Ni relative to Ni-pyz-Ni. Thus, we synthesized two new Q1D chains: staggered [Ni(pym)(H2O)4]SO4●2H2O and chiral [Ni(pym)(H2O)4]SiF6●H2O, each showing multiple field-induced phase transitions below 5 K. Lastly, we will describe a unique 3D chiral Ni(II) framework that may display spin-liquid behavior at low temperatures. Time permitting, the structural and magnetic properties of these materials will be discussed.
*NSF DMR-1703003 (EWU), DMR-1157490 (MagLab), DoE, State of FL, ERC, EPSRC
References:
[1] J. Brambleby, et al. Phys. Rev. B (2017) 95, 134435.
[2] J. Liu, et al. Inorg. Chem. (2016) 55, 3515.
[3] J. L. Manson, et al. Polyhed. (2019) submitted and unpublished work.
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Presenters
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Jamie Manson
- Department of Chemistry and Biochemistry, Eastern Washington University
- Eastern Washington University