Effect of Fe substitution on structure and exchange interactions within and between the sublattices of frustrated CoCr2O4

2020 ◽  
Vol 22 (48) ◽  
pp. 28222-28229
Author(s):  
Canglong Li ◽  
Chunlei Wang ◽  
Qiankun Lei ◽  
Godfrey Okumu Barasa ◽  
Qingshan Fu ◽  
...  
Keyword(s):  
Magnetic Coupling ◽  
Exchange Interactions ◽  
Geometrically Frustrated ◽  
High Interest ◽  
Points Of View ◽  
Magnetic States ◽  
Fe Substitution

Obtaining tunable magnetic states in geometrically frustrated multiferroic compound CoCr2O4 by tuning the sublattice magnetic coupling is indeed of high interest from the fundamental and applied points of view.

Electronic States and Magnetic Coupling in Fe/Fe3O4 Junctions

2011 ◽  
Vol 1292 ◽  
Author(s):  
J. Inoue ◽  
T. Kida ◽  
S. Honda ◽  
H. Itoh ◽  
H. Yanagihara ◽  
...  
Keyword(s):  
Exchange Coupling ◽  
Magnetic Moments ◽  
Magnetic Coupling ◽  
Exchange Interactions ◽  
Coupling Energy ◽  
Local Moments ◽  
Potential Applicability ◽  
Atomic Exchange ◽  
Magnetic States ◽  
Fe Ions

ABSTRACTExchange coupling observed recently in Fe/ Fe3O4 (001) junctions shows comparable intensity to that in Co/Ru/Co trilayers, and has potential applicability to spintronics devices. To clarify the mechanism of the exchange coupling, electronic and magnetic states of Fe/ Fe3O4 junctions are calculated in the first principles method by assuming four junction structures of bcc Fe and Fe3O4 layers. It is shown that the local moments of bcc Fe atoms at the interface increase, but those of Fe ions at the interface of Fe3O4 layer decrease. The total energy of the junctions is plotted as a function of distance between Fe and Fe3O4 layers. Calculated results of the coupling energy between Fe and Fe3O4 layers, however, are larger than experimental ones by two orders of magnitude, and they correspond to inter-atomic exchange interactions at the interface. In order to explain the experimental results, we propose a mechanism of exchange coupling mediated by impurity-like states of interfacial Fe atoms which possess reversed magnetic moments in bcc Fe layer. Frustration effects in exchange coupling between Fe and Fe3O4 layers are also discussed.

Presidential Address: Deeds and Seals

1950 ◽  
Vol 32 ◽  
pp. 141-151 ◽  
Author(s):  
T. F. T. Plucknett
Keyword(s):  
Presidential Address ◽  
Academic Life ◽  
High Interest ◽  
The Subject ◽  
Magnum Opus ◽  
Points Of View

One of the more pleasant aspects of academic life is the informal chat between a professor and a young historian when they plan together a very necessary and illuminating book. It will be agreed that the subject is of high interest from several points of view, that the material is adequate—indeed, abundant, and that it might well prove to be a magnum opus upon which a respectable reputation could be built. Some of the main problems of the subject will be briefly indicated, some daring guesses will emerge (of course, suitably qualified with the remark that ‘there may be nothing in it, but it might be worth looking into’), and a wealth of references will be given to the more obscure foreign periodicals.

Magnetic Exchange Interactions in Geometrically Frustrated Antiferromagnet of ZnCr2−xGaxO4

2018 ◽  
Vol 32 (4) ◽  
pp. 1095-1098
Author(s):  
Jing Yu ◽  
Lichao Wang ◽  
Yao Ying ◽  
Jingwu Zheng ◽  
Wangchang Li ◽  
...  
Keyword(s):  
Exchange Interactions ◽  
Magnetic Exchange ◽  
Geometrically Frustrated

Computational studies of the Mn4/Ca cluster in photosystem II

2018 ◽  
Vol 17 (01) ◽  
pp. 1850007 ◽  
Author(s):  
Bernard Baituti
Keyword(s):  
Dft Calculations ◽  
Closed Form ◽  
Water Oxidation ◽  
Density Functional ◽  
Magnetic Coupling ◽  
Exchange Interactions ◽  
Oxygen Evolving Complex ◽  
International Edition ◽  
Oxygen Evolving ◽  
Closed Form Formula

Computational chemistry with the data from more detailed X-ray diffraction (XRD) oxygen evolving complex (OEC) structure has been used extensively of late in exploring the mechanisms of water oxidation in the OEC. The study reported in this paper involves density functional theory (DFT) calculations to investigate whether the data are in agreement with the four manganese ions in the OEC, being organized as a ‘3[Formula: see text]1’ (trimer plus one) model [Gatt et al. Angewandte Chemie International Edition, 51, 12025–12028, 2012; Petrie et al. Chemistry - A European Journal, 21, 6780–6792, 2015; Terrett et al. Chemical Communications, 50, 3187–3190, 2014] or ‘dimer of dimers’ model. [Terrett et al. Journal of Inorganic Biochemistry, 162, 178–189, 2016]. The data analysis method used involves quantum chemical DFT calculations on relevant models of the OEC cluster. DFT calculations were performed using both the so-called ‘open’ and ‘closed’ forms [Terrett et al. Journal of Inorganic Biochemistry, 162, 178–189, 2016] of the S2 OEC structure models with total spin ([Formula: see text]) 1/2, 7/2, 9/2 and 15/2 within the MnIII MnIV MnIII MnIII ‘low’ oxidation paradigm to examine exchange coupling within the OEC cluster. The results show that the [Formula: see text]-coupling in the ‘closed’ form: [Formula: see text][Formula: see text]cm[Formula: see text], [Formula: see text][Formula: see text]cm[Formula: see text], [Formula: see text][Formula: see text]cm[Formula: see text] and [Formula: see text]–[Formula: see text][Formula: see text]cm[Formula: see text]. In the ‘closed’ form, [Formula: see text] and [Formula: see text] represent the two largest exchange interactions within the manganese cluster, whereas [Formula: see text] and [Formula: see text] are small and almost net cancel. The magnetic coupling between the four Mn ions is close to ‘dimer of dimers’, with both dimers anti-ferromagnetically coupled internally and with weak inter-dimer net coupling.

scholarly journals Guidelines for Selecting Interlayer Spacers in Synthetic 2D-Based Antiferromagnets from First-Principles Simulations

Nanomaterials ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1764
Author(s):  
Ramón Cuadrado ◽  
Miguel Pruneda
Keyword(s):  
Density Functional ◽  
Magnetic Coupling ◽  
Exchange Interactions ◽  
Magnetic Exchange ◽  
Graphene Layers ◽  
Out Of Plane ◽  
Relativistic Description ◽  
Ferromagnetic Interactions ◽  
Exhaustive Study ◽  
Co Coupling

Following the recent synthesis of graphene–based antiferromagnetic ultrathin heterostructures made of Co and Fe, we analyse the effect of the spacer between both ferromagnetic materials. Using density functional calculations, we carried out an exhaustive study of the geometric, electronic and magnetic properties for intercalated single Co MLs on top of Ir(111) coupled to monolayered Fe through n graphene layers (n = 1, 2, 3) or monolayered h-BN. Different local atomic arrangements have been considered to model the Moiré patterns expected in these heterostructures. The magnetic exchange interactions between both ferromagnets ( J C o − F e ) are computed from explicit calculations of parallel and anti-parallel Fe/Co inter–layer alignments, and discussed in the context of recent experiments. Our analysis confirms that the robust antiferromagnetic superexchange–coupling between Fe and Co layers is mediated by the graphene spacer through the hybridization of C’s p z orbitals with Fe and Co’s 3d states. The hybridization is substantially suppressed for multilayered graphene spacers, for which the magnetic coupling between ferromagnets is critically reduced, suggesting the need for ultrathin (monolayer) spacers in the design of synthetic graphene-based antiferromagnets. In the case of h–BN, p z orbitals also mediate d(Fe/Co) coupling. However, there is a larger contribution of local ferromagnetic interactions. Magnetic anisotropy energies were also calculated using a fully relativistic description, and show out–of–plane easy axis for all the configurations, with remarkable net values in the range from 1 to 4 meV.

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