Rotating magnetocaloric effect and unusual magnetic features in metallic strongly anisotropic geometrically frustrated TmB4

Orendáč, M.; Gabáni, S.; Gažo, E.; Pristáš, G.; Shitsevalova, N. Yu.; Siemensmeyer, Konrad; Flachbart, К.

doi:10.1038/s41598-018-29399-2

Cited by 28 publications

(10 citation statements)

References 35 publications

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“…The rotating magnetocaloric effect (RMCE) is a new issue in the magnetic cooling research. In contrast to conventional magnetocaloric effect, in RMCE the change of entropy is obtained not by changing the external magnetic field, but with rotation of a single crystal in a constant magnetic field [59][60][61][62]. If the compound reveals a substantial magnetic anisotropy, then the magnetic entropy will depend on the crystal orientation in the magnetic field.…”

Section: Rotating Magnetocaloric Effect In Anisotropic Two-dimensionamentioning

confidence: 98%

“…Most of the research concerning rotating magnetocaloric effect deals with inorganic materials [59][60][61]63,64,[66][67][68] and there are only few examples related to molecular magnets [69]. In our research we have focused on two-dimensional molecular compounds which reveal magnetic anisotropy and transition to long-range ordered phase.…”

Section: Rotating Magnetocaloric Effect In Anisotropic Two-dimensionamentioning

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: 98%

Section: Rotating Magnetocaloric Effect In Anisotropic Two-dimensionamentioning

confidence: 99%

Multifunctional Molecular Magnets: Magnetocaloric Effect in Octacyanometallates

et al. 2018

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“…The experiment revealed isentropes with a rich structure, which were very well reproduced theoretically by considering a simple Heisenberg spin Hamiltonian with only exchange [17] or including also intra-molecular dipolar interactions [18]. The observed isentropes were concluded to be a direct manifestation of the trigonal antiferromagnetic net structure, which triggered further experimental [19,20] and theoretical [21][22][23][24][25][26][27][28][29][30][31] studies of mainly frustration-enhanced MCE in finite systems of various shapes and topologies. They included geometrically frustrated Ising spin clusters with shapes of regular polyhedra [21,22] or triangular geometry [23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 52%

Effect of Single-ion Anisotropy on Magnetocaloric Properties of Frustrated Spin-$s$ Ising Nanoclusters

Mohylna,

Žukovič

2020

Preprint

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Effects of a single-ion anisotropy on magnetocaloric properties of selected spin-s ≥ 1 antiferromagnetic Ising clusters with frustration-inducing triangular geometry are studied by exact enumeration. It is found that inclusion of the single-ion anisotropy parameter D can result in a much more complex ground-state behavior, which is also reflected in a magnetocaloric effect (MCE) at finite temperatures. For negative D (easy-plane anisotropy) with increasing s the ground-state magnetization as a function of the external field gradually shows increasing number of plateaus of various heights. Except for the cases of integer s with D < D 0 ≤ 0, the first magnetization plateau is of non-zero height. This property facilitates an enhanced MCE in the adiabatic demagnetization process in the form of an abrupt decrease in temperature as the magnetic field vanishes to zero. The cooling rate can be considerably enhanced in the systems with larger s and D > 0 (easy-axis anisotropy), albeit its dependence on these parameters is strongly dependent on the cluster geometry. From the studied systems more favorable conditions for observing a giant MCE were found in the 2CS cluster, consisting of two corner-sharing tetrahedra, the experimental realization of which could be technologically used for efficient refrigeration to ultra-low temperatures.

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“…The experiment revealed isentropes with a rich structure, which were very well reproduced theoretically by considering a simple Heisenberg spin Hamiltonian with only exchange [17] or including also intramolecular dipolar interactions [18]. The observed isentropes were concluded to be a direct manifestation of the trigonal antiferromagnetic net structure, which triggered further experimental [19,20] and theoretical [21][22][23][24][25][26][27][28][29][30][31] studies of mainly frustration-enhanced MCE in finite systems of various shapes and topologies. They included geometrically frustrated Ising spin clusters with shapes of regular polyhedra [21,22] or triangular geometry [23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 54%

Effect of Single-Ion Anisotropy on Magnetocaloric Properties of Frustrated Spin-s Ising Nanoclusters

Mohylna

Žukovič

2020

Magnetochemistry

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Effects of a single-ion anisotropy on magnetocaloric properties of selected spin-s≥1 antiferromagnetic Ising clusters with frustration-inducing triangular geometry are studied by exact enumeration. It is found that inclusion of the single-ion anisotropy parameter D can result in a much more complex ground-state behavior, which is also reflected in a magnetocaloric effect (MCE) at finite temperatures. For negative D (easy-plane anisotropy) with increasing s, the ground-state magnetization as a function of the external field gradually shows increasing number of plateaus of various heights. Except for the cases of integer s with D<D0≤0, the first magnetization plateau is of non-zero height. This property facilitates an enhanced MCE in the adiabatic demagnetization process in the form of an abrupt decrease in temperature as the magnetic field vanishes to zero. The cooling rate can be considerably enhanced in the systems with larger s and D>0 (easy-axis anisotropy), albeit its dependence on these parameters is strongly dependent on the cluster geometry. From the studied systems more favorable conditions for observing a giant MCE were found in the 2CS cluster, consisting of two corner-sharing tetrahedra, the experimental realization of which could be technologically used for efficient refrigeration to ultra-low temperatures.

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Rotating magnetocaloric effect and unusual magnetic features in metallic strongly anisotropic geometrically frustrated TmB4

Cited by 28 publications

References 35 publications

Multifunctional Molecular Magnets: Magnetocaloric Effect in Octacyanometallates

Multifunctional Molecular Magnets: Magnetocaloric Effect in Octacyanometallates

Effect of Single-ion Anisotropy on Magnetocaloric Properties of Frustrated Spin-$s$ Ising Nanoclusters

Effect of Single-Ion Anisotropy on Magnetocaloric Properties of Frustrated Spin-s Ising Nanoclusters

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