Metamagnetic transitions induced by doping with non-magnetic 4+ ions in ludwigites Co5A(O2BO3)2 (A=Zr and Hf)

Anisotropic thermal expansion and electronic transitions in the Co3BO5 ludwigite

“…This type of reasoning fully agrees with actual experimental charge states at metal sites observed in the ludwigites with Me 2+ = Co, Fe, Mn, Cu, Ni, Mg, and Me 3+ = Co, Fe, Mn, Ga, Al, etc. [46][47][48][49][50][51][52][53][54] This is also confirmed by the recent DFT + GGA calculation of the Co 2 FeBO 5 electronic structure, where the cationic and charge distribution effects have been investigated. 46 The electronic states with metal ions Me 3+ = Fe exclusively filling the M4 site and Me 2+ = Co occupying the M1, M2, and M3 sites were found to be energetically favoured.…”

Temperature- and Field-Induced Transformation of the Magnetic State in Co2.5Ge0.5BO5

“…This compound can be envisaged as a solid solution of Co 3 BO 5 with Ge, located at the M4 site. Unlike the double formula Co 5 MeB 2 O 10 proposed in refs − , here, we will use the unit formula of Co 2.5 Ge 0.5 BO 5 similar to the reported Co-substituted ludwigites. ,, Such a representation allows direct comparison of the magnetic moments of the substituted and pure compounds along their easy magnetization directions and, hence, the study of the site-selective substitution effect.…”

“…Ludwigites can be synthesized by the solid-state reaction or flux method. ,,,, In the present work, the single crystals of Co 2.5 Ge 0.5 BO 5 were obtained using flux synthesis from the system 66% mass (Bi 2 Mo 3 O 12 + 2.4·B 2 O 3 + 0.7·Na 2 O) + 34% mass (CoO + B 2 O 3 + GeO 2 ).…”

“…The possible candidates for the tetravalent substitution are listed in Table S1. The cobalt ludwigites substituted by the nonmagnetic ions Zr, Hf, Sn, and Ti have already been reported. − Their magnetic behavior was found to be rather different, turning from a spin-glass state for Co 5 TiB 2 O 10 ( T sg = 19 K), through a metamagnetic transition for Co 5 ZrB 2 O 10 and Co 5 HfB 2 O 10 ( T N = 71 K), to an antiferromagnetic state for Co 5 SnB 2 O 10 ( T N = 82 K).…”

“…Despite numerous experimental data, the mechanisms responsible for the formation of the ground magnetic state and the nature of the electronic and magnetic transitions in Co-containing ludwigites are still unclear. In ref , it was proposed that doping with the open-shell ions d 0 (Zr and Hf) preserves the two-dimensional antiferromagnetic character of the parent ludwigite, while the closed-shell d 10 Sn leads to three-dimensional magnetism. We propose that the ionic size and electroneutrality of the metal ion filling the M4 site should be taken into account.…”