Effect of magnetic frustrations on magnetism of the Fe3BO5 and Co3BO5 ludwigites

Knyazev, Yu, V; Kazak, N., V; Nazarenko, I. I.; Sofronova, S. N.; Rostovtsev, N. D.; Bartolome, J.; Arauzo, A.; Ovchinnikov, S. G. Source: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, 474 493-500; 10.1016/j.jmmm.2018.10.126 MAR 15 2019

The magnetic structures of Fe3BO5 and Co3BO5 ludwigites have been studied experimentally by magnetic measurements and theoretically by the combination of the group theoretical analysis and semi empiric calculations of the superexchange interactions. The different collinear spin configurations in the triads 3-1-3 and 4-2-4 including ferromagnetic, antiferromagnetic and dimer have been considered. For Fe3BO5 the antiferromagnetic state with zero magnetic moment per unit cell, showing the lowest energy, results to be the most probable magnetic ground state. The unusual magnetic structure comprising two virtually independent orthogonal subsystems is formed to avoid heavy frustrations of superexchange interactions between the 3-1-3 and 4-2-4 spin ladders. In Co3BO5 the magnetic frustrations present for the Co3+ high-spin state are quenched for a Co3+ low spin state resulting in the ferrimagnetic long-range order. The obtained results are discussed in comparison with experimental magnetic data.