Magnetic Supramolecular Grid Structures: Intramolecular Coupling of Four Separate Spins

1997 ◽  
Vol 488 ◽  
Author(s):  
O. Waldmann ◽  
J Hassmann ◽  
R. Koch ◽  
P. Müller ◽  
G. S. Hanan ◽  
...  
Keyword(s):  
Coupling Strength ◽  
Antiferromagnetic Coupling ◽  
Metal Centers ◽  
Tetranuclear Complexes

AbstractThe magnetization of novel tetranuclear supramolecular grid structures and their mononuclear analogues was measured. In the tetranuclear complexes with Co2+ or Ni2+ ions an intramolecular antiferromagnetic coupling of the four metal centers is observed. The isotropic coupling strength was determined to be J = -8 K for the Ni2+ grids, and J = -2 K for the Co2+ grids.

Measuring acoustic mode resonance alone as a sensitive technique to extract antiferromagnetic coupling strength

2015 ◽  
Vol 92 (6) ◽  
Author(s):  
Yajun Wei ◽  
Peter Svedlindh ◽  
Mikhail Kostylev ◽  
Mojtaba Ranjbar ◽  
Randy K. Dumas ◽  
...  
Keyword(s):  
Coupling Strength ◽  
Acoustic Mode ◽  
Antiferromagnetic Coupling ◽  
Sensitive Technique

scholarly journals Systematic Raman study of optical phonons in RBa2Cu3O6+δ ( R=Y , Dy, Gd, Sm, Nd): Antiferromagnetic coupling strength versus lattice parameters

2019 ◽  
Vol 99 (9) ◽  
Author(s):  
Silvia Müllner ◽  
Wayne Crump ◽  
Dirk Wulferding ◽  
Benjamin P. P. Mallett ◽  
Peter Lemmens ◽  
...  
Keyword(s):  
Coupling Strength ◽  
Lattice Parameters ◽  
Antiferromagnetic Coupling ◽  
Optical Phonons ◽  
Raman Study

Studies of Exchange Coupling in Fe (001) Whisker/Cr/Fe Structures using BLS and Rheed Techniques.

1993 ◽  
Vol 313 ◽  
Author(s):  
B. Heinrich ◽  
M. From ◽  
J.F. Cochran ◽  
L. X. Liao ◽  
Z. Celiński ◽  
...  
Keyword(s):  
Coupling Strength ◽  
Exchange Coupling ◽  
High Energy ◽  
Variable Number ◽  
Antiferromagnetic Coupling ◽  
Iron Film ◽  
First Principles Calculations ◽  
Iron Whisker ◽  
Short Period ◽  
Coupling Strengths

ABSTRACTThe conditions for an almost perfect growth of smooth Cr (001) films on an iron whisker substrate have been investigated by means of reflection high energy electron diffraction (RHEED). The exchange interaction between 20 Monolayer thick Fe (001) films separated from a bulk whisker Fe (001) substrate by a variable number of Cr (001) Monolayers (ML) has been investigated by means of Brillouin light scattering experiments (BLS). These experiments show unambiguously that the exchange coupling strength between the iron film and the iron whisker can be described by a short wavelength oscillatory term superposed on a slowly varying antiferromagnetic background. The BLS data enabled one to separate the bilinear and the biquadratic contributions to the antiferromagnetic exchange coupling terms. Both the bilinear and the biquadratic coupling strengths exhibited a short period oscillatory dependence on the Cr interlayer thickness (∼2 Monolayers). Maxima in the bilinear antiferromagnetic coupling strength occur for an odd number of Cr Monolayers. This observation is not in agreement with first principles calculations. The first phase inversion has been found to occur between 4 and 5 ML of Cr.

scholarly journals Intramolecular Antiferromagnetic Coupling in Supramolecular Grid Structures withCo2+Metal Centers

1997 ◽  
Vol 78 (17) ◽  
pp. 3390-3393 ◽  
Author(s):  
O. Waldmann ◽  
J. Hassmann ◽  
P. Müller ◽  
G. S. Hanan ◽  
D. Volkmer ◽  
...  
Keyword(s):  
Antiferromagnetic Coupling ◽  
Metal Centers

scholarly journals Synthesis, Single Crystal X-Ray Structure, Theoretical Studies of Triple-{MnIII-Schiff-Base}-Decorated Molybdate

Crystals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 657
Author(s):  
Jian-Chang Xiao ◽  
Qiong Wu ◽  
Yuan Lei ◽  
Jin-Rong Sun ◽  
Fang Jiang ◽  
...  
Keyword(s):  
Schiff Base ◽  
Single Crystal ◽  
Density Functional ◽  
Antiferromagnetic Coupling ◽  
Metal Centers ◽  
X Ray ◽  
Heterometallic Cluster ◽  
Design And Synthesis ◽  
Low Dimensionality ◽  
Potential Energy Landscapes

The design and synthesis of magnets with low dimensionality is currently an attractive research topic. The reaction of a Schiff base metal complex with simple molybdate has led to the formation of a new {MnIII-Schiff-base}-decorated molybdate heterometallic cluster, [{Mn(salpn)(H2O)}3MoO4](CH3COO)·2H2O (1) (salpn = N,N’-(1,3-propylene)bis(salicylideneiminate)). The hybrid aggregate was characterized using a range of methods including elemental analysis, single crystal x-ray diffraction, Infrared spectra (IR) spectroscopy, and x-ray structural analysis. The crystals of 1 are hexagonal: P63/m, a = 14.027(5) Å, c = 17.487(5) Å, V = 1142.6(3) Å3. Structural analyses indicate that we report on the preparation of the first triple metallic-oligomer held by orthomolybdate. Density functional theoretical calculation (DFT) studies have been performed to calculate electronic structure and potential energy landscapes. Additionally, the magnetic property of 1 indicates an antiferromagnetic coupling between the metal centers in the complex.

Bls Studies of Exchange Coupling in The Iron Whisker/Cr/Fe System

1995 ◽  
Vol 384 ◽  
Author(s):  
J.F. Cochran ◽  
K. Totland ◽  
B. Heinrich ◽  
D. Venus ◽  
S. Govorkov
Keyword(s):  
Thin Film ◽  
Coupling Strength ◽  
Kerr Effect ◽  
Exchange Coupling ◽  
Molecular Beam ◽  
Growth Conditions ◽  
Antiferromagnetic Coupling ◽  
Ferromagnetic Coupling ◽  
Film Magnetization

ABSTRACTBrillouin light scattering (BLS) and magneto-optic Kerr effect have been carried out on a series of specimens consisting of a Fe(001) whisker substrate upon which thin Cr(001) and Fe(001) layers have been deposited by means of molecular beam epitaxy in ultrahigh vacuum. The Fe film was 20 monolayers (ML) thick, and the Cr(001) films were grown having various thicknesses. It is demonstrated that BLS thin film frequencies measured in the saturated magnetic state with the thin film magnetization parallel with the applied magnetic field can be used to obtain the exchange coupling strength between the thin film and whisker magnetizations both for antiferromagnetic coupling and for ferromagnetic coupling, provided that the ferromagnetic coupling is not too strong. It is also shown that the coupling strength is extremely sensitive to the quality of the chromium growth: a small deterioration in the growth conditions has been found to reduce the exchange coupling by nearly a factor of two.

Coupling in Fe(2 ML)/V(y ML) and Fe(2 ML)/V(y ML)/Fe(3 ML)/V(y ML) (y ≥ 4) superlattices

Open Physics ◽  
2007 ◽  
Vol 5 (1) ◽  
Author(s):  
Karen Paul
Keyword(s):  
Coupling Strength ◽  
Antiferromagnetic Coupling ◽  
Physical Parameters

AbstractFe(2 ML)/V(y ML) and interleaved Fe(2 ML)/V(y ML)/Fe(3 ML)/V(y ML) superlattice systems with spacer thicknesses, y, (4 ≤ y ≤ 17) were investigated macro-magnetically to estimate the coupling strength and the magnetoresistance in these materials, and particularly in the antiferromagnetically coupled monolayers. The results from the magnetic and magnetoresistive measurements indicate that adding one monolayer of Fe increases the antiferromagnetic coupling and the magnetoresistivity ratio from 0.0075 mJ/m2 at 20 K and 2 % at 10 K for Fe(2 ML)/V(y ML), to 0.05 mJ/m2 and 2.5 % for Fe(2 ML)/V(y ML)/Fe(3 ML)/V(y ML) at the same temperatures. Both systems exhibit in-plane magnetic and magnetoresistive isotropy, therefore the increase of the conferred physical parameters is attributed mainly to the stresses at the interface as governing mechanisms over the magnetoelastic forces.

Synthesis, Single Crystal X-Ray Structure, Hirshfeld Surface Analysis of a New Isopolymolybdate Based Supramolecular Hybrid

2020 ◽  
Vol 842 ◽  
pp. 223-230
Author(s):  
Jian Chang Xiao ◽  
Jun Li ◽  
Jin Rong Sun ◽  
Yan Xu ◽  
Fang Jiang ◽  
...  
Keyword(s):  
Schiff Base ◽  
Single Crystal ◽  
Surface Analysis ◽  
Hirshfeld Surface ◽  
Hirshfeld Surface Analysis ◽  
Antiferromagnetic Coupling ◽  
Metal Centers ◽  
X Ray ◽  
X Ray Crystallography ◽  
Design And Synthesis

Design and synthesis of supramolecular hybrids with low dimensionality is currently an attractive research topic. The reaction of Schiff base metal complex with isopolymolybdate leads to the isolation of a new isopolymolybdate based supramolecular hybrid, [Mn(salen)(H2O)2]2[Mo8O26]Na2·2H2O (1) (salen = N,N'-bis(salicylidene)ethylenediamine). The supramolecular hybrid was characterized by single crystal X-ray structure analyses, elemental analyses and X-ray crystallography. Crystal data for 1: triclinic, P-1, a=10.0206(8)Å, b = 11.7416(10)Å, c= 13.1494(13)Å, V = 1382.8(2)Å3, Z= 1, Rgt(F) = 0.0353 and wRref(F2) = 0.1009. Structural analyses reveal that 1 represents the first example of [Mo8O26]4- chains formed POM-Schiff-base hybrid. Hirshfeld surface analysis and fingerprint plots are used for decoding intermolecular interactions in 1. Additionally, magnetic property of 1 indicates that there is an antiferromagnetic coupling between the metal centers in the complex.

scholarly journals Chiral, Heterometallic Lanthanide–Transition Metal Complexes by Design

Inorganics ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 72 ◽  
Author(s):  
Anders Øwre ◽  
Morten Vinum ◽  
Michal Kern ◽  
Joris van Slageren ◽  
Jesper Bendix ◽  
...  
Keyword(s):  
Transition Metal ◽  
Transition Metal Complexes ◽  
Lewis Acids ◽  
Antiferromagnetic Coupling ◽  
Relaxation Processes ◽  
Coordination Geometry ◽  
Ferromagnetic Coupling ◽  
Metal Acetylacetonates ◽  
Metal Centers ◽  
Tunneling Pathways

Achieving control over coordination geometries in lanthanide complexes remains a challenge to the coordination chemist. This is particularly the case in the field of molecule-based magnetism, where barriers for magnetic relaxation processes as well as tunneling pathways are strongly influenced by the lanthanide coordination geometry. Addressing the challenge of design of 4f-element coordination environments, the ubiquitous Ln(hfac)3 moieties have been shown to be applicable as Lewis acids coordinating transition metal acetylacetonates facially leading to simple, chiral lanthanide–transition metal heterodinuclear complexes. The broad scope of this approach is illustrated by the synthesis of a range of such complexes LnM: LnM(hfac)3(μ2-acac-O,O,O′)3 (Ln = La, Pr, Gd; M = Cr, Fe, Ga), with approximate three-fold symmetry. The complexes have been crystallographically characterized and exhibit polymorphism for some combinations of 4f and 3d metal centers. However, an isostructural set of systems spanning several lanthanides which exhibit spontaneous resolution in the orthorhombic Sohncke space group P212121 is presented here. The electronic structure and ensuing magnetic properties have been studied by EPR spectroscopy and magnetometry. The GdFe, PrFe, and PrCr complexes exhibit ferromagnetic coupling, while GdCr exhibits antiferromagnetic coupling. GdGa exhibits slow relaxation of the magnetization in applied static fields.

Methane activation by ZSM-5-supported transition metal centers

2021 ◽  
Author(s):  
Daniyal Kiani ◽  
Sagar Sourav ◽  
Yadan Tang ◽  
Jonas Baltrusaitis ◽  
Israel E. Wachs
Keyword(s):  
Transition Metal ◽  
Methane Activation ◽  
Group V ◽  
Metal Centers ◽  
Methane Dehydroaromatization

The literature on methane dehydroaromatization (MDA) to benzene using ZSM-5 supported, group V–VIII transition metal-based catalysts (MOx/ZSM-5) is critically reviewed with a focus on in situ and operando molecular insights.

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