scholarly journals Record high magnetic exchange and magnetization blockade in Ln2@C79N (Ln = Gd(iii) and Dy(iii)) molecules: a theoretical perspective

2015 ◽  
Vol 51 (100) ◽  
pp. 17732-17735 ◽  
Author(s):  
Mukesh Kumar Singh ◽  
Neeraj Yadav ◽  
Gopalan Rajaraman
Keyword(s):  
Theoretical Perspective ◽  
Magnetic Coupling ◽  
Magnetic Exchange ◽  
Great Chance ◽  
Strong Exchange ◽  
Paramagnetic Centres

Ln2@C79N EMFs are found to attain the largest magnetic coupling reported to date between Ln-radical paramagnetic centres. The obtained Ucal values are very large, and strong exchange likely to quench the QTM effects offers a great chance to obtain high blocking temperatures.

Theoretical insights into the origin of magnetic exchange and magnetic anisotropy in {ReIV–MII} (M = Mn, Fe, Co, Ni and Cu) single chain magnets

2016 ◽  
Vol 45 (19) ◽  
pp. 8201-8214 ◽  
Author(s):  
Saurabh Kumar Singh ◽  
Kuduva R. Vignesh ◽  
Velloth Archana ◽  
Gopalan Rajaraman
Keyword(s):  
Magnetic Anisotropy ◽  
Exchange Interaction ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Magnetic Coupling ◽  
Single Chain ◽  
Magnetic Exchange Interaction ◽  
Magnetic Exchange ◽  
Single Chain Magnets

Density functional calculations have been performed on a series of {ReIV–MII} (M = Mn(1), Fe(2), Co(3), Ni(4), Cu(5)) complexes to compute the magnetic exchange interaction between the ReIV and MII ions, and understand the mechanism of magnetic coupling in this series.

scholarly journals Substrate-Controlled Magnetism: Fe Nanowires on Vicinal Cu Surfaces

Nanomaterials ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 159 ◽  
Author(s):  
D. Hashemi ◽  
M. J. Waters ◽  
W. Hergert ◽  
J. Kieffer ◽  
V. S. Stepanyuk
Keyword(s):  
Density Functional ◽  
Magnetic Coupling ◽  
Atomic Scale ◽  
Magnetic Interactions ◽  
Critical Temperatures ◽  
Magnetic Exchange ◽  
Functional Theory ◽  
Novel Approach ◽  
The Stability ◽  
Exchange Parameters

Here we present a novel approach to controlling magnetic interactions between atomic-scale nanowires. Our ab initio calculations demonstrate the possibility to tune magnetic properties of Fe nanowires formed on vicinal Cu surfaces. Both intrawire and interwire magnetic exchange parameters are extracted from density functional theory (DFT) calculations. This study suggests that the effective interwire magnetic exchange parameters exhibit Ruderman–Kittel–Kasuya–Yosida-like (RKKY) oscillations as a function of Fe interwire separation. The choice of the vicinal Cu surface offers possibilities for controlling the magnetic coupling. Furthermore, an anisotropic Heisenberg model was used in Monte Carlo simulations to examine the stability of these magnetic configurations at finite temperatures. The predicted critical temperatures of the Fe nanowires on Cu(422) and Cu(533) surfaces are well above room temperature.

scholarly journals Towards a better understanding of magnetic exchange mediated by hydrogen bonds in Mn(iii)/Fe(iii) salen-type supramolecular dimers

2014 ◽  
Vol 43 (41) ◽  
pp. 15602-15616 ◽  
Author(s):  
Ivan Nemec ◽  
Radovan Herchel ◽  
Tomáš Šilha ◽  
Zdeněk Trávníček
Keyword(s):  
Schiff Base ◽  
Hydrogen Bonds ◽  
Dft Calculations ◽  
Magnetic Anisotropy ◽  
Magnetic Coupling ◽  
Magnetic Exchange

Detailed investigations of the magnetic coupling and magnetic anisotropy in a series of Schiff base salen-type Fe(iii) and Mn(iii) complexes, based on SQUID experiments and DFT calculations, are reported.

The positive exchange bias property with hopping switching behavior in van der Waals magnet FeGeTe

2D Materials ◽  
2021 ◽  
Author(s):  
Shaojie Hu ◽  
Xiaomin Cui ◽  
Zengji Yue ◽  
Pangpang Wang ◽  
Lei Guo ◽  
...  
Keyword(s):  
Exchange Bias ◽  
Van Der Waals ◽  
Magnetic Coupling ◽  
Anomalous Hall Effect ◽  
Switching Behavior ◽  
Bias Effect ◽  
Magnetic Exchange ◽  
Exchange Bias Effect ◽  
Coupling Energy ◽  
Surface Magnetization

Abstract The magnetic exchange bias effect is one of the representative interlayer magnetic coupling phenomena and is widely utilized in numerous technological applications. However, its mechanism is still elusive even in a simple magnetic bilayered system because of the complex interface magnetic orders. Van der Waals layered magnetic materials may provide an essential platform for deeply understanding the detailed mechanism of the exchange bias owing to its ideal interface structure. Here we first observed the positive exchange-biased anomalous Hall effect (AHE) with a hopping switching behavior in the FeGeTe Van der Waals nano-flakes. After systemically studying the cooling field dependence properties of the exchange bias effect, we propose that the coexistence of stable and frustrated surface magnetization of the antiferromagnetic phase will modify the total interface coupling energy density between the ferromagnetic (FM) and antiferromagnetic (AFM) phases. This model could provide a consistent description for such unusual exchange bias effect based on microspin simulation.

Tailor-Made Strong Exchange Magnetic Coupling through Very Long Bridging Ligands:  Theoretical Predictions

2003 ◽  
Vol 42 (16) ◽  
pp. 4881-4884 ◽  
Author(s):  
Eliseo Ruiz ◽  
Antonio Rodríguez-Fortea ◽  
Santiago Alvarez
Keyword(s):  
Magnetic Coupling ◽  
Bridging Ligands ◽  
Theoretical Predictions ◽  
Strong Exchange

Intra-molecular magnetic exchange interaction in the tripyridinium bis[tetrachloroferrate(iii)] chloride molecular magnet: a broken symmetry-DFT study

2015 ◽  
Vol 17 (29) ◽  
pp. 19119-19125 ◽  
Author(s):  
F. Baniasadi ◽  
M. M. Tehranchi ◽  
M. B. Fathi ◽  
N. Safari ◽  
V. Amani
Keyword(s):  
Magnetic Coupling ◽  
Dft Method ◽  
Broken Symmetry ◽  
Molecular Magnet ◽  
Coupling Constant ◽  
Magnetic Exchange Interaction ◽  
Magnetic Exchange ◽  
Electronic Spin ◽  
Density Maps ◽  
Magnetic Coupling Constant

A superexchange interaction path between Fe–Fe in (FeCl4)2(py·H)3Cl is illustrated making use of electronic spin density maps (ESDM) and the magnetic coupling constant is calculated using the BS-DFT method as JFe–Fe = 13.2062 kJ mol−1.

scholarly journals Detection of Pinholes in Ultrathin Films by Magnetic Coupling

2001 ◽  
Vol 674 ◽  
Author(s):  
W. F. Egelhoff ◽  
L. Gan ◽  
P. J. Chen ◽  
C. J. Powell ◽  
R. D. Mcmichael ◽  
...  
Keyword(s):  
Ultrathin Films ◽  
Exchange Bias ◽  
Exchange Coupling ◽  
Magnetic Coupling ◽  
Orange Peel ◽  
Magnetic Films ◽  
Magnetic Exchange ◽  
Cu Films ◽  
Low Field ◽  
Magnetic Exchange Coupling

ABSTRACTWhen two magnetic films are separated by a nonmagnetic film, pinholes in the nonmagnetic film can allow direct contact and, thereby, direct magnetic exchange coupling between the two magnetic films. We have studied this coupling by having one of the magnetic films pinned and leaving the other free to switch at low field. The pinning is accomplished with test structures based on exchange bias and synthetic antiferromagnetic layers. Since the pinning strength increases sharply at low temperatures but orange-peel coupling does not, low-temperature (77 K) measurements appear to identify whether an observed coupling arises primarily from magnetic coupling through pinholes or primarily from orange-peel roughness. Our measurements appear to indicate that the observed coupling arises primarily from magnetic coupling through pinholes for Cu films less than 2.1 nm thick and for Al2O3films less than 0.6 nm thick but primarily from roughness-induced (orange-peel) magnetostatic coupling for larger thicknesses.

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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