Low temperature magnetic and Mössbauer studies on anhydrous iron(II) sulfonates

1986 ◽  
Vol 64 (4) ◽  
pp. 744-750 ◽  
Author(s):  
John S. Haynes ◽  
John R. Sams ◽  
Robert C. Thompson
Keyword(s):  
Variable Temperature ◽  
Magnetic Moments ◽  
Magnetic Ordering ◽  
Singlet Ground State ◽  
Axial Field ◽  
Sharp Drop ◽  
Mössbauer Studies ◽  
Applied Fields ◽  
Orbital Singlet ◽  
Ordered State

Magnetic susceptibilities from 130 to 4.2 K are reported for a series of Fe(RSO3)2 compounds, where R is F, CF3, CH3, and p-CH3C6H4. The β form of Fe(CH3SO3)2 exhibits a maximum in susceptibility at approximately 22.5 K and a sharp drop in susceptibility below the maximum indicating a transition to a magnetically ordered state. None of the other compounds exhibit magnetic ordering although abnormally low magnetic moments down to 2.0 K are observed for α-Fe(CH3SO3)2. Variable-temperature Mössbauer studies on Fe(CF3SO3)2 and β- and α-Fe(CH3SO3)2 are reported and the magnitude of axial field splitting is estimated for these compounds. The first two have trigonally elongated FeO6 chromophores, whereas the third is trigonally compressed. The nature of the distortion in α-Fe(CH3SO3)2 is confirmed by magnetic perturbation Mössbauer studies. Spectra in applied fields of 4.50 and 5.63 T show a doublet–triplet pattern, with the triplet at higher energy, indicating a negative Vzz and an orbital singlet ground state.

scholarly journals Revealing noncollinear magnetic ordering at the atomic scale via XMCD

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Fridtjof Kielgast ◽  
Ivan Baev ◽  
Torben Beeck ◽  
Federico Pressacco ◽  
Michael Martins
Keyword(s):  
Ground State ◽  
Magnetic Circular Dichroism ◽  
Magnetic Moments ◽  
Magnetic Ordering ◽  
Atomic Scale ◽  
Angle Of Incidence ◽  
X Ray ◽  
First Time ◽  
X Ray Absorption ◽  
Magnetic Sublattices

AbstractMass-selected V and Fe monomers, as well as the heterodimer $${\text{Fe}}_1{\text{V}}_1$$ Fe 1 V 1 , were deposited on a Cu(001) surface. Their electronic and magnetic properties were investigated via X-ray absorption (XAS) and X-ray magnetic circular dichroism (XMCD) spectroscopy. Anisotropies in the magnetic moments of the deposited species could be examined by means of angle resolving XMCD, i.e. changing the X-ray angle of incidence. A weak adatom-substrate-coupling was found for both elements and, using group theoretical arguments, the ground state symmetries of the adatoms were determined. For the dimer, a switching from antiparallel to parallel orientation of the respective magnetic moments was observed. We show that this is due to the existence of a noncollinear spin-flop phase in the deposited dimers, which could be observed for the first time in such a small system. Making use of the two magnetic sublattices model, we were able to find the relative orientations for the dimer magnetic moments for different incidence angles.

scholarly journals Open-shell Donors and Closed-shell Acceptors in Organic Solar Cells

2021 ◽  
Author(s):  
Zhongxin Chen ◽  
Yuan Li ◽  
Wenqiang Li ◽  
Weiya Zhu ◽  
Miao Zeng ◽  
...  
Keyword(s):  
Solar Cells ◽  
Electron Spin Resonance ◽  
Electron Spin ◽  
Organic Solar Cells ◽  
Ground State ◽  
Variable Temperature ◽  
Closed Shell ◽  
Open Shell ◽  
Singlet Ground State ◽  
Spin Resonance

The active materials of organic solar cells are widely recognized to show closed-shell singlet ground state and their electron spin resonance signals are attributed to the defects and impurities. Herein, we disclose the inherent open-shell singlet ground state of donors and the closed-shell structure of acceptors via the combination of variable temperature NMR, electron spin resonance, superconducting quantum interference device and theoretical calculation, providing a new perspective to understand the intrinsic molecular structure in organic solar cells.

Novel Magnetic Orders and Ice Phases in Frustrated Kondo-Lattice Models

SPIN ◽  
2015 ◽  
Vol 05 (02) ◽  
pp. 1540006 ◽  
Author(s):  
Gia-Wei Chern
Keyword(s):  
Berry Phase ◽  
Magnetic Moments ◽  
Lattice Models ◽  
Magnetic Ordering ◽  
Double Exchange ◽  
Salient Feature ◽  
Kondo Lattice ◽  
Spin Ice ◽  
Water Ice ◽  
Ising Magnets

We review recent theoretical progress in our understanding of electron-driven novel magnetic phases on frustrated lattices. Our specific focus is on Kondo-lattice or double-exchange models assuming finite magnetic moments localized at the lattice sites. A salient feature of systems with SU(2) symmetric local moments is the emergence of noncoplanar magnetic ordering driven by the conduction electrons. The complex spin textures then endow the electrons a nontrivial Berry phase, often giving rise to a topologically nontrivial electronic state. The second part of the review is devoted to the discussion of metallic spin ice systems, which are essentially frustrated Ising magnets with local spin ordering governed by the so-called ice rules. These rules are similar to those that describe proton configurations in solid water ice, hence the name "spin ice". The nontrivial spin correlations in the ice phase give rise to unusual electron transport properties in metallic spin-ice systems.

scholarly journals Probing magnetism in atomically thin semiconducting PtSe2

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Ahmet Avsar ◽  
Cheol-Yeon Cheon ◽  
Michele Pizzochero ◽  
Mukesh Tripathi ◽  
Alberto Ciarrocchi ◽  
...  
Keyword(s):  
Long Range ◽  
Magnetic Moments ◽  
Transition Metal Dichalcogenides ◽  
Magnetic Ordering ◽  
Atomic Scale ◽  
First Principles Calculations ◽  
Microscopy Imaging ◽  
Transmission Electron ◽  
Metal Dichalcogenides ◽  
The One

Abstract Atomic-scale disorder in two-dimensional transition metal dichalcogenides is often accompanied by local magnetic moments, which can conceivably induce long-range magnetic ordering into intrinsically non-magnetic materials. Here, we demonstrate the signature of long-range magnetic orderings in defective mono- and bi-layer semiconducting PtSe2 by performing magnetoresistance measurements under both lateral and vertical measurement configurations. As the material is thinned down from bi- to mono-layer thickness, we observe a ferromagnetic-to-antiferromagnetic crossover, a behavior which is opposite to the one observed in the prototypical 2D magnet CrI3. Our first-principles calculations, supported by aberration-corrected transmission electron microscopy imaging of point defects, associate this transition to the interplay between the defect-induced magnetism and the interlayer interactions in PtSe2. Furthermore, we show that graphene can be effectively used to probe the magnetization of adjacent semiconducting PtSe2. Our findings in an ultimately scaled monolayer system lay the foundation for atom-by-atom engineering of magnetism in otherwise non-magnetic 2D materials.

scholarly journals Mössbauer Spectroscopic Studies of Molecule-Based Magnets: Two-Dimensional Complexes Derived from Metal Schiff-Bases and Hexacyanoferrate(III)

2002 ◽  
Vol 57 (6-7) ◽  
pp. 603-606 ◽  
Author(s):  
S. Iijima ◽  
F. Mizutani ◽  
H. Miyasaka ◽  
N. Matsumoto ◽  
H. Ōkawa
Keyword(s):  
Long Range ◽  
Schiff Bases ◽  
Applied Field ◽  
Variable Temperature ◽  
Magnetic Ordering ◽  
Spectroscopic Studies ◽  
Paramagnetic State ◽  
Two Dimensional ◽  
Mössbauer Measurements

Variable-temperature 57Fe Mössbauer measurements on cyanide-bridged 2-D bimetallic assemblies NEt4[Mn(salen)]2[Fe(CN)6] (1), K[Mn(3-MeOsalen)]2[Fe(CN)6] (2) and K[Mn(3- MeOsalen)]2[Fe(CN)6]2 DMF (3), where salen2- = N,N'-ethylenebis(salicylidene iminato) dianion, revealed that these compounds exhibit a long range magnetic ordering below ca. 10 K under zero applied field. The quadrupole splittings of 1 - 3 showed intermediate values between those of typical cyano-bridged 1-D and 3-D complexes. The paramagnetic state of K[Mn(5-Clsalen)]2- [Fe(CN)6] 4 H2O (4) turned to a bulk magnetic one with desolvation

Field-induced magnetic ordering in the singlet-ground state system Ni(C5H5NO)6(ClO4)2 studied by specific heat

Physica B+C ◽  
1976 ◽  
Vol 85 (2) ◽  
pp. 323-326 ◽  
Author(s):  
H.A. Algra ◽  
J. Bartolomé ◽  
K.M. Diederix ◽  
L.J. De Jongh ◽  
R.L. Carlin
Keyword(s):  
Specific Heat ◽  
Ground State ◽  
Magnetic Ordering ◽  
State System ◽  
Singlet Ground State

MAGNETIC ORDERING IN QUASICRYSTALS

2005 ◽  
Vol 19 (27) ◽  
pp. 1367-1385 ◽  
Author(s):  
E. Y. VEDMEDENKO
Keyword(s):  
Magnetic Moments ◽  
Ground States ◽  
Magnetic Ordering ◽  
Single Sample ◽  
Magnetic Frustration ◽  
Two Dimensional ◽  
Theoretical Evidence ◽  
Quasiperiodic Tilings ◽  
Magnetically Ordered

An overview of the theoretical advances in description of the magnetic ordering and its stability in two-dimensional quasiperiodic tilings with strongly localized magnetic moments is presented. It is demonstrated that combination of the magnetic frustration and the quasiperiodic order of atoms leads to noncollinear ground states. An experimental and theoretical evidence for the possibility of coexistence of stable, magnetically ordered subtilings with highly frustrated, glass-like phases in a single sample is given.

MAGNETIC TRANSITION IN QUASI ONE DIMENSIONAL WIRES AND THIN FILMS OF GADOLINIUM

1993 ◽  
Vol 07 (01n03) ◽  
pp. 496-499
Author(s):  
NAUSHAD ALI ◽  
J. T. MASDEN ◽  
PEGGY HILL ◽  
ARTHUR CHIN
Keyword(s):  
Thin Films ◽  
Magnetic Transition ◽  
High Vacuum ◽  
Magnetic Ordering ◽  
Ultra High Vacuum ◽  
Vacuum System ◽  
Ferromagnetic Transition ◽  
Sharp Drop ◽  
Cross Sectional ◽  
Thin Wires

Thin wires of gadolinium metal have been fabricated using a step lithographic technique with cross-sectional areas from 0.87 × 10−11 cm 2 to 58 × 10−11 cm 2. The thin films of gadolinium were deposited in a ultra high vacuum system by thermal evaporation with the thickness of films in the range 200Å to 1200Å. Resistivity data of Gd thin wires does not show evidence of bulk transition at T c ≈ 293 K (bulk) at all. However, a phase transition manifested as a sharp drop in resistivity of Gd thin wires is observed around 20 K. Thin films of Gd deposited on glass and sapphire substrates were used to measure the magnetic properties using a SQUID magnetometer. Films of thickness > 500Å show ferromagnetic transition around 290 K (close to bulk) and a small peak in the magnetization around 20 K is also observed. For Gd films of thickness ~ 200Å there is no evidence of ferromagnetic transition, however, the magnetization data clearly shows a peak in the neighborhood of 20 K. It appears that in the case of very thin films and thin wires of Gd we are observing a magnetic transition around 20 K. This transition may be due to magnetic ordering of the surface which has a transition temperature much smaller than the bulk ferromagnetic T c of 293 K.

Implications of Interfacial Coupling and Strain on the Magnetic and Structural Ordering of Fe3O4/NiO Superlattices

1994 ◽  
Vol 341 ◽  
Author(s):  
David M. Lind
Keyword(s):  
Molecular Beam ◽  
Magnetic Moments ◽  
Magnetic Ordering ◽  
Interlayer Coupling ◽  
Verwey Transition ◽  
Interfacial Coupling ◽  
Adjacent Layer ◽  
Structural Ordering ◽  
X Ray

AbstractHere we review recent work on the preparation and characterization of magnetically ordered oxide Fe3O4/NiO superlattices. The materials were prepared by oxygen plasma-assisted molecular beam epitaxy. Their structural ordering was studied by x-ray, neutron, and RHEED electron diffraction techniques, and the superlattices are found to form as highly coherent strained-layer modulated single crystals. The magnetic ordering studies, using SQUID magnetometry, ferromagnetic resonance, and neutron diffraction, indicated strong interfacial coupling between the ferrimagnetic Fe3O4 layers and the antiferromagnetic NiO layers, with the magnetic ordering in each layer altered by the proximity to the magnetic moments in the adjacent layer. Strain and other layer-thickness effects are also evident in these magnetic layered structures. The special influence of interlayer coupling and strain on the Fe3O4 Verwey transition are discussed.

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