High-Coercivity Ferrimagnet Co₂FeO₂BO₃: XMCD Insights into Charge-Ordering and Cation Distribution
The multi-sublattice ferrimagnet Co<sub>2</sub>FeO<sub>2</sub>BO<sub>3</sub>, a prominent example of lanthanide-free magnets, was the subject of element-selective studies using X-ray magnetic circular dichroism (XMCD) observations at the <i>L</i>- and...
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| author | Mikhail S. Platunov |
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| description | The multi-sublattice ferrimagnet Co<sub>2</sub>FeO<sub>2</sub>BO<sub>3</sub>, a prominent example of lanthanide-free magnets, was the subject of element-selective studies using X-ray magnetic circular dichroism (XMCD) observations at the <i>L</i>- and <i>K</i>- X-ray absorption edges. Research findings indicate that the distinct magnetic characteristics of Co<sub>2</sub>FeO<sub>2</sub>BO<sub>3</sub>, namely its remarkable high coercivity (which surpasses 7 Tesla at low temperatures), originate from an atypical arrangement of magnetic ions in the crystal structure (sp.gr. <i>Pbam</i>). The antiferromagnetic nature of the Co<sup>2+</sup>-O-Fe<sup>3+</sup> exchange interaction was confirmed by identifying the spin and orbital contributions to the total magnetization from Co (m<sub>L</sub> = 0.27 ± 0.1 μ<sub>B</sub>/ion and m<sup>eff</sup><sub>S</sub> = 0.53 ± 0.1 μ<sub>B</sub>/ion) and Fe (m<sub>L</sub> = 0.05 ± 0.1 μ<sub>B</sub>/ion and m<sup>eff</sup><sub>S</sub> = 0.80 ± 0.1 μ<sub>B</sub>/ion) ions through element-selective XMCD analysis. Additionally, the research explicitly revealed that the strong magnetic anisotropy is a result of the significant unquenched orbital magnetic moment of Co, a feature that is also present in the related compound Co<sub>3</sub>O<sub>2</sub>BO<sub>3</sub>. A complex magnetic structure in Co<sub>2</sub>FeO<sub>2</sub>BO<sub>3</sub>, with infinite Co²⁺O<sub>6</sub> layers in the <b>bc</b>-plane and strong antiferromagnetic coupling through Fe<sup>3</sup>⁺ ions, is suggested by element-selective hysteresis data, which revealed that Co²⁺ ions contribute both antiferromagnetic and ferromagnetic components to the total magnetization. The findings underline the suitability of Co<sub>2</sub>FeO<sub>2</sub>BO<sub>3</sub> for applications in extreme environments, such as low temperatures and high magnetic fields, where its unique magnetic topology and anisotropy can be harnessed for advanced technologies, including materials for space exploration and quantum devices. This XMCD study opens the door to the production of novel high-coercivity, lanthanide-free magnetic materials by showing that targeted substitution at specific crystallographic sites can significantly enhance the magnetic properties of such materials. |
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| spelling | doaj-art-8b62698d4edd4696af018174358a4e352025-01-24T13:35:31ZengMDPI AGInorganics2304-67402025-01-011312410.3390/inorganics13010024High-Coercivity Ferrimagnet Co₂FeO₂BO₃: XMCD Insights into Charge-Ordering and Cation DistributionMikhail S. Platunov0Synchrotron Radiation Facility SKIF, Kol’tsovo 630559, RussiaThe multi-sublattice ferrimagnet Co<sub>2</sub>FeO<sub>2</sub>BO<sub>3</sub>, a prominent example of lanthanide-free magnets, was the subject of element-selective studies using X-ray magnetic circular dichroism (XMCD) observations at the <i>L</i>- and <i>K</i>- X-ray absorption edges. Research findings indicate that the distinct magnetic characteristics of Co<sub>2</sub>FeO<sub>2</sub>BO<sub>3</sub>, namely its remarkable high coercivity (which surpasses 7 Tesla at low temperatures), originate from an atypical arrangement of magnetic ions in the crystal structure (sp.gr. <i>Pbam</i>). The antiferromagnetic nature of the Co<sup>2+</sup>-O-Fe<sup>3+</sup> exchange interaction was confirmed by identifying the spin and orbital contributions to the total magnetization from Co (m<sub>L</sub> = 0.27 ± 0.1 μ<sub>B</sub>/ion and m<sup>eff</sup><sub>S</sub> = 0.53 ± 0.1 μ<sub>B</sub>/ion) and Fe (m<sub>L</sub> = 0.05 ± 0.1 μ<sub>B</sub>/ion and m<sup>eff</sup><sub>S</sub> = 0.80 ± 0.1 μ<sub>B</sub>/ion) ions through element-selective XMCD analysis. Additionally, the research explicitly revealed that the strong magnetic anisotropy is a result of the significant unquenched orbital magnetic moment of Co, a feature that is also present in the related compound Co<sub>3</sub>O<sub>2</sub>BO<sub>3</sub>. A complex magnetic structure in Co<sub>2</sub>FeO<sub>2</sub>BO<sub>3</sub>, with infinite Co²⁺O<sub>6</sub> layers in the <b>bc</b>-plane and strong antiferromagnetic coupling through Fe<sup>3</sup>⁺ ions, is suggested by element-selective hysteresis data, which revealed that Co²⁺ ions contribute both antiferromagnetic and ferromagnetic components to the total magnetization. The findings underline the suitability of Co<sub>2</sub>FeO<sub>2</sub>BO<sub>3</sub> for applications in extreme environments, such as low temperatures and high magnetic fields, where its unique magnetic topology and anisotropy can be harnessed for advanced technologies, including materials for space exploration and quantum devices. This XMCD study opens the door to the production of novel high-coercivity, lanthanide-free magnetic materials by showing that targeted substitution at specific crystallographic sites can significantly enhance the magnetic properties of such materials.https://www.mdpi.com/2304-6740/13/1/24magnetismcoercive fieldelement-specificityorbital-specificitycharge ordering |
| spellingShingle | Mikhail S. Platunov High-Coercivity Ferrimagnet Co₂FeO₂BO₃: XMCD Insights into Charge-Ordering and Cation Distribution Inorganics magnetism coercive field element-specificity orbital-specificity charge ordering |
| title | High-Coercivity Ferrimagnet Co₂FeO₂BO₃: XMCD Insights into Charge-Ordering and Cation Distribution |
| title_full | High-Coercivity Ferrimagnet Co₂FeO₂BO₃: XMCD Insights into Charge-Ordering and Cation Distribution |
| title_fullStr | High-Coercivity Ferrimagnet Co₂FeO₂BO₃: XMCD Insights into Charge-Ordering and Cation Distribution |
| title_full_unstemmed | High-Coercivity Ferrimagnet Co₂FeO₂BO₃: XMCD Insights into Charge-Ordering and Cation Distribution |
| title_short | High-Coercivity Ferrimagnet Co₂FeO₂BO₃: XMCD Insights into Charge-Ordering and Cation Distribution |
| title_sort | high coercivity ferrimagnet co₂feo₂bo₃ xmcd insights into charge ordering and cation distribution |
| topic | magnetism coercive field element-specificity orbital-specificity charge ordering |
| url | https://www.mdpi.com/2304-6740/13/1/24 |
| work_keys_str_mv | AT mikhailsplatunov highcoercivityferrimagnetco2feo2bo3xmcdinsightsintochargeorderingandcationdistribution |