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Understanding the relationship between the local crystal structure and the ferrimagnetic ordering of CoxMn3-xO4 (x = 0–0.5) solid solutions
Journal of Alloys and Compounds ( IF 6.2 ) Pub Date : 2021-02-01 , DOI: 10.1016/j.jallcom.2020.157256
Narayanan Kutty Rajeesh Kumar , Leonid Vasylechko , Shailja Sharma , Chandra S. Yadav , Ramakrishnan Kalai Selvan

Abstract The local crystal structure alterations in the tetrahedral positions of the hausmannite Mn3O4 structure by Co2+ ions and its consequence on the magnetic ordering are studied in detail. The cation composition, bond distance and bond angle of the CoxMn3-xO4 series (x = 0.0. 0.1, 0.3 and 0.5) is determined by XRD Rietveld refinement. The charge state of the elements Co, Mn and O are investigated using XPS measurements, which confirm the bivalent cobalt ion occupation in the tetrahedral lattice. Considerable reduction in tetrahedral and axial octahedral bonds with the introduction of Co2+ ions dramatically increased the Curie temperature (TC) from 43 K (Mn3O4) to 62 K (Co0.5Mn2.5O4). The Lotgering-Srinivasan-Seehra model is employed to study the canted spin arrangement and the exchange interactions of Co0.5Mn2.5O4. The presence of cluster glass transition at TP = 42 K in Co0.3Mn2.7O4 is well-established through the AC susceptibility measurements and it is further substantiated by Vogel-Fulcher law and dynamic scaling power law. The origin of the cluster glass state is confirmed by the calculated strong geometric frustration factor (f = 19.5), due to the inhomogeneous distribution of cobalt ions in the intermediate concentrations. Field cooled isothermal magnetic measurements corroborated the exchange bias phenomenon in the Co0.3Mn2.7O4 sample, because of the interaction between ferrimagnetic-cluster glass phases occurring below the spin freezing temperature TP.

中文翻译:

了解局部晶体结构与 CoxMn3-xO4 (x = 0-0.5) 固溶体的亚铁磁性排序之间的关系

摘要 详细研究了Co2+离子对铁锰矿Mn3O4结构四面体位置的局部晶体结构改变及其对磁序的影响。CoxMn3-xO4 系列 (x = 0.0、0.1、0.3 和 0.5) 的阳离子组成、键距和键角由 XRD Rietveld 精修确定。使用 XPS 测量来研究元素 Co、Mn 和 O 的电荷状态,这证实了四面体晶格中的二价钴离子占据。随着 Co2+ 离子的引入,四面体和轴向八面体键的显着减少使居里温度 (TC) 从 43 K (Mn3O4) 显着增加到 62 K (Co0.5Mn2.5O4)。Lotgering-Srinivasan-Seehra 模型用于研究Co0.5Mn2.5O4 的倾斜自旋排列和交换相互作用。Co0.3Mn2.7O4 中 TP = 42 K 处的簇玻璃化转变的存在通过 AC 磁化率测量得到了很好的证实,并且由 Vogel-Fulcher 定律和动态缩放幂定律进一步证实。由于钴离子在中间浓度的不均匀分布,计算出的强几何挫折因子 (f = 19.5) 证实了团簇玻璃态的起源。场冷却等温磁测量证实了 Co0.3Mn2.7O4 样品中的交换偏置现象,因为亚铁磁团簇玻璃相之间的相互作用发生在自旋冻结温度 TP 以下。由于钴离子在中间浓度的不均匀分布,计算出的强几何挫折因子 (f = 19.5) 证实了团簇玻璃态的起源。场冷却等温磁测量证实了 Co0.3Mn2.7O4 样品中的交换偏置现象,因为亚铁磁团簇玻璃相之间的相互作用发生在自旋冻结温度 TP 以下。由于钴离子在中间浓度的不均匀分布,计算出的强几何挫折因子 (f = 19.5) 证实了团簇玻璃态的起源。场冷却等温磁测量证实了 Co0.3Mn2.7O4 样品中的交换偏置现象,因为亚铁磁团簇玻璃相之间的相互作用发生在自旋冻结温度 TP 以下。
更新日期:2021-02-01
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