scholarly journals Dinuclear molecular magnets with unblocked magnetic connectivity: magnetocaloric effect

RSC Advances ◽  
2018 ◽  
Vol 8 (26) ◽  
pp. 14640-14645 ◽  
Author(s):  
Magdalena Fitta ◽  
Robert Pełka ◽  
Wojciech Sas ◽  
Dawid Pinkowicz ◽  
Barbara Sieklucka
Keyword(s):  
Magnetocaloric Effect ◽  
Molecular Magnets

The study of magnetocaloric effect in two related bimetallic cyanide-bridged molecular magnets: {[M (H2O)2]2[Nb (CN)8]·4H2O}n (M = Mn, Fe) is presented.

scholarly journals Giant and time-dependent magnetocaloric effect in high-spin molecular magnets

2000 ◽  
Vol 77 (20) ◽  
pp. 3248-3250 ◽  
Author(s):  
F. Torres ◽  
J. M. Hernández ◽  
X. Bohigas ◽  
J. Tejada
Keyword(s):  
Magnetocaloric Effect ◽  
High Spin ◽  
Molecular Magnets ◽  
Time Dependent

scholarly journals Rotational magnetocaloric effect of anisotropic giant-spin molecular magnets

2019 ◽  
Vol 482 ◽  
pp. 113-119 ◽  
Author(s):  
Christian Beckmann ◽  
Julian Ehrens ◽  
Jürgen Schnack
Keyword(s):  
Magnetocaloric Effect ◽  
Molecular Magnets

scholarly journals Multifunctional Molecular Magnets: Magnetocaloric Effect in Octacyanometallates

Crystals ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 9 ◽  
Author(s):  
Magdalena Fitta ◽  
Robert Pełka ◽  
Piotr Konieczny ◽  
Maria Bałanda
Keyword(s):  
Magnetocaloric Effect ◽  
Metal Ion ◽  
Chemical Properties ◽  
Magnetic Ordering ◽  
Entropy Change ◽  
Building Blocks ◽  
Molecular Magnets ◽  
Characteristic Index ◽  
A New Technique ◽  
Physical And Chemical

Octacyanometallate-based compounds displaying a rich pallet of interesting physical and chemical properties, are key materials in the field of molecular magnetism. The [M(CN)8]n− complexes, (M = WV, MoV, NbIV), are universal building blocks as they lead to various spatial structures, depending on the surrounding ligands and the choice of the metal ion. One of the functionalities of the octacyanometallate-based coordination polymers or clusters is the magnetocaloric effect (MCE), consisting in a change of the material temperature upon the application of a magnetic field. In this review, we focus on different approaches to MCE investigation. We present examples of magnetic entropy change ΔSm and adiabatic temperature change ΔTad, determined using calorimetric measurements supplemented with the algebraic extrapolation of the data down to 0 K. At the field change of 5T, the compound built of high spin clusters Ni9[W(CN)8]6 showed a maximum value of −ΔSm equal to 18.38 J·K−1 mol−1 at 4.3 K, while the corresponding maximum ΔTad = 4.6 K was attained at 2.2 K. These values revealed that this molecular material may be treated as a possible candidate for cryogenic magnetic cooling. Values obtained for ferrimagnetic polymers at temperatures close to their magnetic ordering temperatures, Tc, were lower, i.e., −ΔSm = 6.83 J·K−1 mol−1 (ΔTad = 1.42 K) and −ΔSm = 4.9 J·K−1 mol−1 (ΔTad = 2 K) for {[MnII(pyrazole)4]2[NbIV(CN)8]·4H2O}n and{[FeII(pyrazole)4]2[NbIV(CN)8]·4H2O}n, respectively. MCE results have been obtained also for other -[Nb(CN)8]-based manganese polymers, showing significant Tc dependence on pressure or the remarkable magnetic sponge behaviour. Using the data obtained for compounds with different Tc, due to dissimilar ligands or other phase of the material, the ΔSm ~ Tc−2/3 relation stemming from the molecular field theory was confirmed. The characteristic index n in the ΔSm ~ ΔHn dependence, and the critical exponents, related to n, were determined, pointing to the 3D Heisenberg model as the most adequate for the description of these particular compounds. At last, results of the rotating magnetocaloric effect (RMCE), which is a new technique efficient in the case of layered magnetic systems, are presented. Data have been obtained and discussed for single crystals of two 2D molecular magnets: ferrimagnetic {MnII(R-mpm)2]2[NbIV(CN)8]}∙4H2O (mpm = α-methyl-2-pyridinemethanol) and a strongly anisotropic (tetren)Cu4[W(CN)8]4 bilayered magnet showing the topological Berezinskii-Kosterlitz-Thouless transition.

Exchange Spin Coupling from Gaussian Process Regression

2020 ◽  
Author(s):  
Marc Philipp Bahlke ◽  
Natnael Mogos ◽  
Jonny Proppe ◽  
Carmen Herrmann
Keyword(s):  
Machine Learning ◽  
Gaussian Process ◽  
Gaussian Process Regression ◽  
Molecular Magnets ◽  
Molecular Structures ◽  
Spin Coupling ◽  
Structure Property ◽  
Data Set ◽  
Uncertainty Estimates

Heisenberg exchange spin coupling between metal centers is essential for describing and understanding the electronic structure of many molecular catalysts, metalloenzymes, and molecular magnets for potential application in information technology. We explore the machine-learnability of exchange spin coupling, which has not been studied yet. We employ Gaussian process regression since it can potentially deal with small training sets (as likely associated with the rather complex molecular structures required for exploring spin coupling) and since it provides uncertainty estimates (“error bars”) along with predicted values. We compare a range of descriptors and kernels for 257 small dicopper complexes and find that a simple descriptor based on chemical intuition, consisting only of copper-bridge angles and copper-copper distances, clearly outperforms several more sophisticated descriptors when it comes to extrapolating towards larger experimentally relevant complexes. Exchange spin coupling is similarly easy to learn as the polarizability, while learning dipole moments is much harder. The strength of the sophisticated descriptors lies in their ability to linearize structure-property relationships, to the point that a simple linear ridge regression performs just as well as the kernel-based machine-learning model for our small dicopper data set. The superior extrapolation performance of the simple descriptor is unique to exchange spin coupling, reinforcing the crucial role of choosing a suitable descriptor, and highlighting the interesting question of the role of chemical intuition vs. systematic or automated selection of features for machine learning in chemistry and material science.

Magnetocaloric Effect in Metamagnetic Shape Memory Alloy

2020 ◽  
Vol 12 (1) ◽  
pp. 01018-1-01018-4
Author(s):  
Anna Kosogor ◽  
◽  
Serafima I. Palamarchuk ◽  
Victor A. Lvov ◽  
◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Magnetocaloric Effect

Giant Magnetocaloric Effect of Tmcosi Compound Under Low Field Change

2020 ◽  
Author(s):  
Jia-Wang Xu ◽  
Xinqi Zheng ◽  
Shu-Xian Yang ◽  
L. Xi ◽  
J. Y. Zhang ◽  
...  
Keyword(s):  
Magnetocaloric Effect ◽  
Field Change ◽  
Low Field ◽  
Giant Magnetocaloric Effect

Magnetism and magnetocaloric effect in the RE2CuSi3 (RE = Dy and Ho) compounds

2017 ◽  
Vol 702 ◽  
pp. 546-550 ◽  
Author(s):  
Yikun Zhang ◽  
Dan Guo ◽  
Yang Yang ◽  
Shuhua Geng ◽  
Xi Li ◽  
...  
Keyword(s):  
Magnetocaloric Effect

Effect of substitution of In for Co on magnetostructural coupling and magnetocaloric effect in MnCo1-xInxGe compounds

2014 ◽  
Vol 115 (17) ◽  
pp. 17A911 ◽  
Author(s):  
R. R. Wu ◽  
L. F. Bao ◽  
F. X. Hu ◽  
J. Wang ◽  
X. Q. Zheng ◽  
...  
Keyword(s):  
Magnetocaloric Effect
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