Magnetic dynamics of NiMn2O4 spinel produced by a simple aqueous sol-gel route

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

卷:538

Article

Cabral, A. J. Freitas¹  Serna, J. D. Pena²  Salles, Benjamin Rache²  Amorim, H. S.²  Rem, C. M. Rocha³  Novak, A. Miguel² 

[1] Univ Fed Oeste Para UFOPA, Santarem, PA, Brazil

[2] Univ Fed Rio de Janeiro, Inst Fis, Caixa Postal 68528, BR-21941972 Rio de Janeiro, RJ, Brazil

[3] Univ Fed Para UFPA, Inst Ciencias Exatas & Nat, Belem, PA, Brazil

关键词: Nickel manganite;    Sol-gel method;    Magnetic properties;    Relaxation processes;    Exchange bias;   

DOI  :  10.1016/j.jmmm.2021.168291

来源: Elsevier

【 摘 要 】

Polycrystalline nickel manganite was prepared by a simple sol-gel method from an aqueous solution of metal chlorides containing sorbitol as a chelating agent. X-ray diffraction and Rietveld refinement show a spinel-type crystalline structure, space group Fd3m, and a minor (similar to 3%) phase of rock salt structure assigned to NiO. XPS measurement shows a typical manganite electronic structure with Mn in the oxidation states Mn2+, Mn3+, and Mn4+. The zero-field-cooled and field-cooled magnetization curves measured under low magnetic fields display irreversibility and an asymmetric hysteresis evidencing some exchange bias. Field dependent DC susceptibility above Curie temperature put into evidence a competition of short ranged ferro and antiferromagnetic interactions. AC in-phase susceptibility shows a frequency independent sharp peak at the ferromagnetic phase transition (97 K) and a broad maximum at lower temperature. These maxima show a weak frequency dependence in the out-phase component. Cole-Cole plot reveals at least two magnetic relaxation processes.

【 授权许可】

Free