Canted ferrimagnetism in the distorted double perovskite La3Mn2NbO9.

The synthesis, structural characterization, and magnetic properties of La 3 Mn 2 NbO 9 double perovskite are reported. The crystal structure has been refined by X-ray and neutron powder diffraction data in the monoclinic space group P2 1 /n. The Mn2+, Mn3+ and Nb5+ cations are distributed at the 2d and 2c Wyckoff sites, with a high cation order degree in the latter, mainly occupied by Mn2+/Mn3+. The Mn3+ presence was established from X-ray Emission Spectroscopy and X-ray Photoelectron Spectroscopy. Rietveld refinements of powder neutron diffraction data show that at room temperature the cell parameters are a= 5.6063(3) Å, b= 5.8155(3) Å, c= 7.9877(2) Å y β= 89.89(1)°. Magnetization measurements indicate the presence of ferromagnetic and antiferromagnetic interactions with T C ∼19 K and T N ∼11 K, respectively, with a magnetic cell of symmetry Γ 1 (A g). The analysis of the neutron data suggests a canted ferrimagnetic spin structure where an antiferromagnetic unit-cell in a and c axis, and ferromagnetic in b axis with a propagation vector k = (0 ½ 0) was used. The effective magnetic moment obtained experimentally is μ eff = 5.50 μ B /mol Mn2+/3+, slightly lower than the theoretical one for spin only (5.83 μ B). • Synthesis of new double perovskite La 3 Mn 2 NbO 9. • Canted ferrimagnetism due to the high degree of structural distortion. • Effective existence of Mn2+/Mn3+ mixture. • Multiple possible magnetic interactions and huge distortion of the octahedral network allow AFM and FM couplings. [ABSTRACT FROM AUTHOR]