Self-Enhancement of Rotating Magnetocaloric Effect in Anisotropic Two-Dimensional (2D) Cyanido-Bridged Mn<sup>II</sup>–Nb<sup>IV</sup> Molecular Ferrimagnet

Konieczny, P.; Michalski, Łukasz; Podgajny, Robert; Chorąży, Szymon; Pełka, Robert; Czernia, Dominik; Buda, Szymon; Młynarski, Jacek; Sieklucka, Barbara; Wasiutyński, T.

doi:10.1021/acs.inorgchem.6b02941

Cited by 20 publications

(13 citation statements)

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“…Nevertheless, the compound reveals a phase transition to 3D long-range magnetic ordered state at T c = 23.5 K due to intermolecular dipole-dipole interactions. The magnetic single crystal measurements of 10 showed an easy-plane type anisotropy within the layers, whereas the perpendicular direction was a hard axis [72]. The observed anisotropy was not significant, since above 0.35 T applied field both orientations was magnetically undistinguishable.…”

Section: Rotating Magnetocaloric Effect In Anisotropic Two-dimensionamentioning

confidence: 86%

“…Crystals 2018, 8, x 28 of 33 Figure 30.Temperature dependence of percentage ratio between ΔSRMCE and ΔSeasy (easy plane) for 10 for different fields. Adapted with permission from Reference [72]. Copyright 2017 American Chemical Society.…”

Section: Rotating Magnetocaloric Effect In Anisotropic Two-dimensionamentioning

confidence: 99%

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confidence: 99%

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Multifunctional Molecular Magnets: Magnetocaloric Effect in Octacyanometallates

et al. 2018

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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.

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Section: Rotating Magnetocaloric Effect In Anisotropic Two-dimensionamentioning

confidence: 86%

Section: Rotating Magnetocaloric Effect In Anisotropic Two-dimensionamentioning

confidence: 99%

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Multifunctional Molecular Magnets: Magnetocaloric Effect in Octacyanometallates

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“…MCE quantifies the thermal response of a magnetic material caused by a varying magnetic field. The rotating magnetocaloric effect (RMCE) is a new direction in magnetic refrigeration that has drawn strong interest recently [6][7][8][9][10][11][12][13] . The conventional MCE utilises a change in the magnetic entropy on variation of a magnetic field.…”

Section: Introductionmentioning

confidence: 99%

Rotating magnetocaloric effect in the ferromagnetic Weyl semi-metal Co3Sn2S2

Ali

Shama

Singh

2019

Journal of Applied Physics

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The rotating magnetocaloric effect (RMCE) is a recent interest in magnetic refrigeration technique in which the cooling effect is attained by rotating the anisotropic magnetocaloric material from one orientation to the other in a fixed magnetic field. In this work, we report the anisotropic magnetocaloric properties of single crystals of the ferromagnetic Weyl semimetal Co3Sn2S2 for magnetic field H c axis and H ab plane. We observed a significant (factor of 2) difference between the magnetocaloric effect measured in both orientations. The rotating magnetocaloric effect has been extracted by taking the difference of the magnetic entropy change (∆SM ) for fields applied in the two crystallographic orientations. In a scaling analysis of ∆SM , the rescaled ∆SM (T, H) vs reduced temperature θ curves collapse onto a single universal curve, indicating that the transition from paramagnetic to ferromagnetic phase at 174 K is a second order transition. Furthermore, using the power law dependence of ∆SM and relative cooling power RCP, the critical exponents β and γ are calculated, which are consistent with the recent critical behavior study on this compound 1 .

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“…In our previous work, we have studied the RMCE in a 2D cyanido-bridged Mn II −Nb IV (MnNb) molecular ferrimagnet with easy-plane anisotropy. 53 In this type of anisotropy, the magnetic moments, which preferably are lying within the easy plane, can be distorted by applying a magnetic field perpendicular to this layer and therefore increasing the magnetic disorder. This phenomenon, where the external magnetic field increases the magnetic entropy, is known as the inverse magnetocaloric effect, and we have shown it can be used to enhance the RMCE.…”

Section: ■ Introductionmentioning

confidence: 99%

Rotating Magnetocaloric Effect in an Anisotropic Two-Dimensional Cu^II[W^V(CN)₈]^3– Molecular Magnet with Topological Phase Transition: Experiment and Theory

et al. 2017

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Conventional (MCE) and rotating (RMCE) magnetocaloric effects have been explored in the two-dimensional (2D) coordination polymer {(tetren)H)Cu[W(CN)]·7.2HO} (WCu-t; tetren = tetraethylenepentamine). The unusual magnetostructural properties were exploited, including the bilayered Prussian Blue like coordination skeleton and the XY easy-plane magnetic anisotropy based on the in-plane correlation between W and Cu spins of /, underlying the Berezinskii-Kosterlitz-Thouless (BKT) topological phase transition to the long-range-ordered state at T = 33 K. The magnetic properties were studied on single crystals along the H∥ac easy plane and H∥b hard axis. The maximal entropy change for MCE for easy-plane geometry at 38.0 K and the magnetic field change μΔH = 7.0 T reached ∼4.01 J K kg. The strong magnetic anisotropy was used to study the RMCE in which the maximal entropy change was observed at 35.5 K for 7.0 T, attaining 1.81 J K kg. Moreover, easy-plane anisotropy introduces the inverse magnetocaloric effect for H∥b, which enhances the RMCE by up to 47%. This observation was confirmed by a theoretical investigation considering the XY model using a molecular field and cluster variational method in the pair approximation approach, dedicated to the bilayered systems with the adequate nearest neighbor number z = 5 and spin S = /.

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Self-Enhancement of Rotating Magnetocaloric Effect in Anisotropic Two-Dimensional (2D) Cyanido-Bridged Mn^II–Nb^IV Molecular Ferrimagnet

Cited by 20 publications

References 53 publications

Multifunctional Molecular Magnets: Magnetocaloric Effect in Octacyanometallates

Multifunctional Molecular Magnets: Magnetocaloric Effect in Octacyanometallates

Rotating magnetocaloric effect in the ferromagnetic Weyl semi-metal Co3Sn2S2

Rotating Magnetocaloric Effect in an Anisotropic Two-Dimensional Cu^II[W^V(CN)₈]^3– Molecular Magnet with Topological Phase Transition: Experiment and Theory

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Self-Enhancement of Rotating Magnetocaloric Effect in Anisotropic Two-Dimensional (2D) Cyanido-Bridged MnII–NbIV Molecular Ferrimagnet

Cited by 20 publications

References 53 publications

Multifunctional Molecular Magnets: Magnetocaloric Effect in Octacyanometallates

Multifunctional Molecular Magnets: Magnetocaloric Effect in Octacyanometallates

Rotating magnetocaloric effect in the ferromagnetic Weyl semi-metal Co3Sn2S2

Rotating Magnetocaloric Effect in an Anisotropic Two-Dimensional CuII[WV(CN)8]3– Molecular Magnet with Topological Phase Transition: Experiment and Theory

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Self-Enhancement of Rotating Magnetocaloric Effect in Anisotropic Two-Dimensional (2D) Cyanido-Bridged Mn^II–Nb^IV Molecular Ferrimagnet

Rotating Magnetocaloric Effect in an Anisotropic Two-Dimensional Cu^II[W^V(CN)₈]^3– Molecular Magnet with Topological Phase Transition: Experiment and Theory