Magnetostructural correlations for Fe 2+ ions at orthorhombic sites in FeCl 2 ·4H 2 O and FeF 2 ·4H 2 O crystals modeled by microscopic spin Hamiltonian approach

Comparative Analysis of Experimental and Theoretical Zero-Field Splitting and Zeeman Electronic Parameters for Fe2+ Ions in FeX2·4H2O (X = F, Cl, Br, I) and [Fe(H2O)6](NH4)2(SO4)2

“…The spin Hamiltonian (SH) parameters, including the zero-field splitting (ZFS) and the Zeeman electronic (Ze) parameters [1,2], have recently been modeled for Fe 2+ ions in FeX 2 · 4H 2 O (X = F, Cl, Br, I) crystals, which exhibit similar crystal structure -see [3] for references. High-magnetic field and high-frequency EMR (HMF-EMR) techniques (for references, see, e.g.…”

“…[4][5][6]) provide nowadays more reliable experimental ZFS and Ze parameter sets for 3d 4 and 3d 6 (S = 2) ions, e.g. Fe 2+ , Mn 3+ , and Cr 2+ , which usually exhibit large and very large ZFS [3,7]. Similar modeling, using the package MSH/VBA [8,9] based on the microscopic spin Hamiltonian (MSH) approach, has recently been undertaken for [Fe(H 2 O) 6 ](NH 4 ) 2 (SO4) 2 (FASH) [10][11][12].…”

“…The microscopic SH (MSH) approach incorporates MSH expressions for the ZFS and Ze parameters up to fourth-order perturbation theory suitable for of 3d 4 and 3d 6 ions with spin S = 2 at orthorhombic and tetragonal symmetry sites in crystals, which exhibit an orbital singlet ground state arising from the ground 5 D multiplet [8,9]. The aim of this paper is to provide a comparative analysis of experimental and theoretical ZFS and Ze parameters for Fe 2+ ions in FeCl 2 ·4H 2 O [3] and FASH. Pertinent theoretical background and references on the crystalfield (CF) Hamiltonian, H CF and H SH = H Ze + H ZF S , * corresponding author; e-mail: Magdalena.Zajac@zut.edu.pl which underlie this study, may be found in [3].…”

“…The aim of this paper is to provide a comparative analysis of experimental and theoretical ZFS and Ze parameters for Fe 2+ ions in FeCl 2 ·4H 2 O [3] and FASH. Pertinent theoretical background and references on the crystalfield (CF) Hamiltonian, H CF and H SH = H Ze + H ZF S , * corresponding author; e-mail: Magdalena.Zajac@zut.edu.pl which underlie this study, may be found in [3]. We note only that for both Hamiltonians we utilize the extended Stevens operators (ESO) O q k [13,14].…”

“…The ZFSP values for Fe 2+ in FASH were determined by HMF-EMR [12] as (in cm −1 ): |b 0 2 | = 14.94(2) and |b 2 2 | = 11.335. Only scant spectroscopic data are available for FeF 2 · 4H 2 O [3,26], which provided determination of the first few optical transitions. More relevant data exist for FASH obtained from the Mössbauer and IR spectroscopy, e.g.…”