Controlling Magnetic Anisotropy in a Zero-Dimensional S = 1 Magnet Using Isotropic Cation Substitution

Jamie L Manson; Samuel P M Curley; Robert C Williams; David Walker; Paul A Goddard; Andrew Ozarowski; Roger D Johnson; Anuradha M Vibhakar; Danielle Y Villa; Melissa L Rhodehouse; Serena M Birnbaum; John Singleton

doi:10.1021/jacs.0c12516

Controlling Magnetic Anisotropy in a Zero-Dimensional S = 1 Magnet Using Isotropic Cation Substitution

J Am Chem Soc. 2021 Mar 31;143(12):4633-4638. doi: 10.1021/jacs.0c12516. Epub 2021 Mar 16.

Affiliations

¹ Department of Chemistry, Biochemistry & Physics, Eastern Washington University, Cheney, Washington 99004, United States.
² Department of Physics, University of Warwick, Coventry CV4 7AL, U.K.
³ National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States.
⁴ Department of Physics & Astronomy, University College London, London WC1E 6BT, U.K.
⁵ Clarendon Laboratory, Department of Physics, Oxford University, Oxford OX1 3PU, U.K.
⁶ National High Magnetic Field Laboratory, Pulsed-Field Facility, MS-E536, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States.

Abstract

The [Zn_1-xNi_x(HF₂)(pyz)₂]SbF₆ (x = 0.2; pyz = pyrazine) solid solution exhibits a zero-field splitting (D) that is 22% larger [D = 16.2(2) K (11.3(2) cm^-1)] than that observed in the x = 1 material [D = 13.3(1) K (9.2(1) cm^-1)]. The substantial change in D is accomplished by an anisotropic lattice expansion in the MN₄ (M = Zn or Ni) plane, wherein the increased concentration of isotropic Zn(II) ions induces a nonlinear variation in M-F and M-N bond lengths. In this, we exploit the relative donor atom hardness, where M-F and M-N form strong ionic and weak coordinate covalent bonds, respectively, the latter being more sensitive to substitution of Ni by the slightly larger Zn(II) ion. In this way, we are able to tune the single-ion anisotropy of a magnetic lattice site by Zn-substitution on nearby sites. This effect has possible applications in the field of single-ion magnets and the design of other molecule-based magnetic systems.