Role of High-Spin Molecules as Models for Organic Ferro- and Ferri-Magnets, and Pi-Toporegulated Magnetic Polymers

1989 ◽  
Vol 173 ◽  
Author(s):  
Takeji Takui ◽  
Makoto Endoh ◽  
Masayuki Okamoto ◽  
Kazunobu Satoh ◽  
Toyohiro Shichiri ◽  
...  
Keyword(s):  
Chemical Modification ◽  
Single Crystal ◽  
High Spin ◽  
Spin Structure ◽  
Esr Spectroscopy ◽  
Model Compounds ◽  
Spin Alignment ◽  
Methylene Bridge ◽  
Spin Structures

ABSTRACTA chemical modification exploiting functional groups such as ether and methylene as bridges between high-spin assemblies has been carried out as a usable method to increase dimensionality of spin structure. Exchange interaction via an ether or a methylene bridge between two high-spin assemblies has been studied by single-crystal ESR spectroscopy. Whether it is ferromagnetic or antiferromagnetic depends upon the substituted position of the bridge, demonstrating the important role of the topological nature in spin alignment. It turns out that superexchange interaction or hyperconjugation mechanism can dominate spin alignment between high-spin assemblies. Using the criteria obtained, model compounds for units of organic ferrimagnets have been synthesized. They possess antiferromagnetically-exchange coupled heterospins and the salient features of their spin structures are characterized in terms of the spin density distribution as determined by single-crystal 1H-ENDOR (Electron-Nuclear-DOuble Resonance) spectroscopy.

Role of Topology in Spin Alignment of Organic Materials

1989 ◽  
Vol 173 ◽  
Author(s):  
Koichi Itoh ◽  
Takeji Takui ◽  
Yoshio Teki ◽  
Takamasa Kinoshita
Keyword(s):  
Single Crystal ◽  
High Spin ◽  
Organic Molecules ◽  
Valence Bond ◽  
Spin Alignment ◽  
Remarkable Feature ◽  
Density Distributions ◽  
Generalized Hubbard Model ◽  
State Spin

ABSTRACTIt is shown that the spin alignment in organic molecules as determined by single crystal ESR is highly dependent on the topological nature of their molecular pi electron networks. The three topological isomers of a high-spin molecule, biphenyl-n,n′-bis(phenylmethylene), abbreviated as BP-3,3′-BPM, BP-3,4′-BPM and BP-4,4′-BPM are taken as model compounds. BP-3,3′-BPM has a unique spin alignment for which the simple molecular orbital and valence bond methods predict different ground-state spin multiplicities. The above remarkable feature of spin alignment in organic high-spin molecule is interpreted in terms of their spin density distributions which have been determined by a single crystal ENDOR technique and compared with theoretical values calculated on the basis of a generalized Hubbard model as well as the Heisenberg model. This approach is extended to magnetic polymers in order to characterize their structure of the spin sites.

Ground-state high-spin iron (III) octaethylporphyrin as studied by single-crystal cw/pulsed ESR spectroscopy

2001 ◽  
Vol 121 (1-3) ◽  
pp. 1820-1821 ◽  
Author(s):  
T. Nishio ◽  
S. Yokoyama ◽  
K. Sato ◽  
D. Shiomi ◽  
A.S. Ichimura ◽  
...  
Keyword(s):  
Single Crystal ◽  
High Spin ◽  
Ground State ◽  
Esr Spectroscopy ◽  
High Spin Iron

High-spin structures inSm137: Role of theβ-driving νi13/2intruder in deformation enhancement

1989 ◽  
Vol 40 (1) ◽  
pp. 156-167 ◽  
Author(s):  
R. Ma ◽  
C. W. Beausang ◽  
E. S. Paul ◽  
W. F. Piel ◽  
S. Shi ◽  
...  
Keyword(s):  
High Spin ◽  
Spin Structures

High-spin structure of the neutron-rich 107,109 45Rh isotopes: the role of triaxiality

1999 ◽  
Vol 6 (4) ◽  
pp. 405-413 ◽  
Author(s):  
Ts. Venkova ◽  
M.-G. Porquet ◽  
I. Deloncle ◽  
B.J.P. Gall ◽  
H. De Witte ◽  
...  
Keyword(s):  
High Spin ◽  
Spin Structure

Structural, magnetic and Mössbauer spectroscopic studies of the [Fe(3-bpp)2](CF3COO)2 complex: role of crystal packing leading to an incomplete Fe(ii) high spin ⇋ low spin transition

CrystEngComm ◽  
2021 ◽  
Vol 23 (15) ◽  
pp. 2854-2861
Author(s):  
Kristian Handoyo Sugiyarto ◽  
Djulia Onggo ◽  
Hiroki Akutsu ◽  
Varimalla Raghavendra Reddy ◽  
Hari Sutrisno ◽  
...  
Keyword(s):  
High Spin ◽  
Crystal Packing ◽  
Spin Transition ◽  
Spectroscopic Studies ◽  
Mononuclear Complex

Mononuclear complex [Fe(3-bpp)2](CF3COO)2 exhibits a thermal (HS + HS) ⇋ (HS + LS) transition at ∼226 K which is not associated with any crystallographic transition.

scholarly journals Modeling of magneto-conductivity of bismuth selenide: a topological insulator

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Yogesh Kumar ◽  
Rabia Sultana ◽  
Prince Sharma ◽  
V. P. S. Awana
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Single Crystal ◽  
Single Crystals ◽  
X Ray Diffraction ◽  
Field Range ◽  
X Ray ◽  
Bulk Carriers ◽  
Different Temperatures

AbstractWe report the magneto-conductivity analysis of Bi2Se3 single crystal at different temperatures in a magnetic field range of ± 14 T. The single crystals are grown by the self-flux method and characterized through X-ray diffraction, Scanning Electron Microscopy, and Raman Spectroscopy. The single crystals show magnetoresistance (MR%) of around 380% at a magnetic field of 14 T and a temperature of 5 K. The Hikami–Larkin–Nagaoka (HLN) equation has been used to fit the magneto-conductivity (MC) data. However, the HLN fitted curve deviates at higher magnetic fields above 1 T, suggesting that the role of surface-driven conductivity suppresses with an increasing magnetic field. This article proposes a speculative model comprising of surface-driven HLN and added quantum diffusive and bulk carriers-driven classical terms. The model successfully explains the MC of the Bi2Se3 single crystal at various temperatures (5–200 K) and applied magnetic fields (up to 14 T).

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