Crystal growth, structure, magnetic properties and theoretical exchange interaction calculations of Cu2MnBO5

Single crystals of ludwigite Cu2MnBO5 were synthesized by flux growth technique. The detailed structural and magnetic characterizations of the synthesized samples have been carried out. The cations composition of the studied crystal was determined using X-ray diffraction and EXAFS technique, the resulting composition differ from the content of the initial Mn2O3–CuO components of the flux. Magnetic susceptibility measurements and the calculations of the exchange integrals in frameworks of indirect coupling model revealed that monoclinic distortions strongly affect exchange interactions and appearance of magnetic ordering phase at the temperature T=93 K. The hypothesis of the existence of several magnetic subsystems was supposed

Transformation of structure and magnetic properties of Cu2MnBO5 under partial Mn3+ -> Fe3+ substitution

Single crystals of Fe-substituted Cu(2)Mn(1-x)FexBO(5) ludwigites have been synthesized using flux technique (x = 0.2, 0.4, 0.5 - in the initial flux system). Structural properties of the synthesized compounds were studied by the single crystal and powder X-ray diffraction analysis. Obtained results were analyzed in the relationship with parent compound Cu2MnBO5. It was revealed that the type of monoclinic distortions of Fe-substituted ludwigites is different from the structure of Cu2MnBO5. The real cation composition and local structure of Cu(2)Mn(1-x)FexBO(5) ludwigites were studied using XANES and EXAFS techniques, respectively. Analysis of field and thermal dependencies of magnetization showed a high dependence of the magnetic properties of these ludwigites on x with changing the type of magnetic ordering

New national and regional bryophyte records, 47

International audience[No abstract available