Magnetic Interactions in the Double Perovskites R2NiMnO6 (R = Tb, Ho, Er, Tm) Investigated by Neutron Diffraction

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• 作者：Mar铆a Retuerto ; 脕ngel Mu帽oz ; Mar铆a Jes煤s Mart铆nez-Lope ; Jos茅 Antonio Alonso ; Federico J. Mompe谩n ; Mar铆a Teresa Fern谩ndez-D铆az ; Javier S谩nchez-Ben铆tez
• 刊名：Inorganic Chemistry
• 出版年：2015
• 出版时间：November 16, 2015
• 年：2015
• 卷：54
• 期：22
• 页码：10890-10900
• 全文大小：605K
• ISSN：1520-510X

文摘

R₂NiMnO₆ (R = Tb, Ho, Er, Tm) perovskites have been prepared by soft-chemistry techniques followed by high oxygen-pressure treatments; they have been investigated by X-ray diffraction, neutron powder diffraction (NPD), and magnetic measurements. In all cases the crystal structure is defined in the monoclinic P2₁/n space group, with an almost complete order between Ni²⁺ and Mn⁴⁺ cations in the octahedral perovskite sublattice. The low temperature NPD data and the macroscopic magnetic measurements indicate that all the compounds are ferrimagnetic, with a net magnetic moment different from zero and a distinct alignment of Ni and Mn spins depending on the nature of the rare-earth cation. The magnetic structures are different from the one previously reported for La₂NiMnO₆, with a ferromagnetic structure involving Mn⁴⁺ and Ni²⁺ moments. This spin alignment can be rationalized taking into account the Goodenough鈥揔anamori rules. The magnetic ordering temperature (T_CM) decreases abruptly as the size of the rare earth decreases, since T_CM is mainly influenced by the superexchange interaction between Ni²⁺ and Mn⁴⁺ (Ni²⁺鈥揙鈥揗n⁴⁺ angle) and this angle decreases with the rare-earth size. The rare-earth magnetic moments participate in the magnetic structures immediately below T_CM.