Ferromagnetic Mn3+ Sawtooth Chains in A2(Mn2O)(SeO3)3 (A = K, Rb) Quaternary Selenites
Yaping Li1, Feifan Li2, Olivier Mentré3
1School of Environmental & Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, Jiangsu, China.
Inorganic Chemistry
|May 24, 2024
Summary
Two new quaternary manganese selenites exhibit complex triclinic structures with ferromagnetic interactions within sawtooth chains. These chains order antiferromagnetically at 22 K, with DFT+U+SOC calculations revealing significant magnetocrystalline anisotropy.
Area of Science:
- Inorganic Chemistry
- Solid-State Chemistry
- Magnetism
Background:
- Quaternary manganese selenites represent a class of materials with potential magnetic properties.
- Understanding the structure-property relationships in these compounds is crucial for developing new magnetic materials.
Purpose of the Study:
- To synthesize and characterize novel quaternary manganese selenites.
- To investigate the magnetic interactions and structural properties of these compounds.
- To explore the role of specific structural motifs, like Jahn-Teller distorted octahedra and sawtooth chains, on magnetic ordering.
Main Methods:
- Hydrothermal synthesis for material preparation.
- X-ray crystallography for structural determination (triclinic, P-1).
- Density Functional Theory (DFT) with the Hubbard U (DFT+U) correction for calculating electronic structure and magnetic exchange interactions.
- Monte Carlo simulations for fitting magnetic exchange parameters.
- Experimental verification of magnetic ordering temperatures (Néel temperature, T_N).
- DFT with spin-orbit coupling (DFT+U+SOC) for magnetocrystalline anisotropy calculations.
Main Results:
- Synthesis of two quaternary manganese selenites, K2(Mn2O)(SeO3)3 and Rb2(Mn2O)(SeO3)3.
- Complex triclinic crystal structure featuring Jahn-Teller distorted Mn3+O4+2 octahedra forming sawtooth (ST) chains.
- Predominant ferromagnetic (FM) interactions within the ST chains, confirmed by calculations and experiments.
- Antiferromagnetic ordering between ST chains at T_N ≈ 22 K.
- Quantification of spin exchanges using DFT+U and Monte Carlo simulations.
- Identification of the μ3-O bridge's role in FM exchanges and observation of spin reorientations.
- Significant magnetocrystalline anisotropy along the [110] direction (~50 meV/Mn) due to spin-orbit coupling.
Conclusions:
- The synthesized manganese selenites possess unique crystal structures that dictate their magnetic behavior.
- Ferromagnetic interactions within sawtooth chains are a key feature, leading to overall antiferromagnetic ordering.
- Computational methods (DFT+U, DFT+U+SOC) are effective in predicting and explaining the magnetic properties, including anisotropy.
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