Single‐Chain Magnets

Pedersen, Kasper S.; Vindigni, Alessandro; Sessoli, Roberta; Coulon, C.; Clérac, Rodolphe

doi:10.1002/9783527694228.ch6

Cited by 21 publications

(19 citation statements)

References 92 publications

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“…Accordingly, for a single-chain magnet, a plot of ln(c M ' T) vs. 1/T should feature a linear region with positive slope corresponding to the correlation energy. [20] To investigate the one-dimensional magnetism of compounds 3 and 4, variable-temperature alternating current (ac) susceptibility data were collected with a 3-Oe ac field oscillating at 1 Hz in the absence of a dc field. The resulting plots of ln(c M ' T) vs. 1/T (Figure 2, insets) indeed feature a linear region of positive slope that confirms the one-dimensional nature of the magnetism in both chain compounds.…”

Section: Resultsmentioning

confidence: 99%

Coercive Fields Above 6 T in Two Cobalt(II)–Radical Chain Compounds

et al. 2020

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Lanthanide permanent magnets are widely used in applications ranging from nanotechnology to industrial engineering. However, limited access to the rare earths and rising costs associated with their extraction are spurring interest in the development of lanthanide‐free hard magnets. Zero‐ and one‐dimensional magnetic materials are intriguing alternatives due to their low densities, structural and chemical versatility, and the typically mild, bottom‐up nature of their synthesis. Here, we present two one‐dimensional cobalt(II) systems Co(hfac)2(R‐NapNIT) (R‐NapNIT=2‐(2′‐(R‐)naphthyl)‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide, R=MeO or EtO) supported by air‐stable nitronyl nitroxide radicals. These compounds are single‐chain magnets and exhibit wide, square magnetic hysteresis below 14 K, with giant coercive fields up to 65 or 102 kOe measured using static or pulsed high magnetic fields, respectively. Magnetic, spectroscopic, and computational studies suggest that the record coercivities derive not from three‐dimensional ordering but from the interaction of adjacent chains that compose alternating magnetic sublattices generated by crystallographic symmetry.

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Section: Resultsmentioning

confidence: 99%

Coercive Fields Above 6 T in Two Cobalt(II)–Radical Chain Compounds

et al. 2020

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“…Thus, the broad DWs (Figure b), where numerous magnetic centers are consistently coupled via the exchange interactions, are attained when the magnetic anisotropy energy is present but significantly smaller than the exchange interaction. Moreover, Δ A decreases with consistently decreasing the |2 E |/ J ratio and finally vanishes in the limit of broad DWs (|2 E | < < 4 J /3) . Therefore, the magnetic anisotropy barriers Δ A of two SCMs are quite small.…”

Section: Resultsmentioning

confidence: 97%

“…Moreover, Δ A decreases with consistently decreasing the |2E|/J ratio and finally vanishes in the limit of broad DWs (|2E| < < 4J/3). 46 Therefore, the magnetic anisotropy barriers Δ A of two SCMs are quite small.…”

Section: Resultsmentioning

confidence: 99%

Origin of Magnetic Relaxation Barriers in a Family of Cobalt(II)–Radical Single-Chain Magnets: Density Functional Theory and Ab Initio Calculations

Lü

Guo

et al. 2021

Inorg. Chem.

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Density functional theory (DFT) and ab initio calculations were performed to probe the origin of the magnetic relaxation barriers for two finite single-chain magnets (SCMs) featuring a one-dimension chain, Co(hfac)2(R-NapNIT) (R-NapNIT = 2-(2′-(R-)naphthyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, R = MeO (1) or EtO (2)). Our calculations show that the strong intrachain CoII–CoII exchange coupling interactions transmitted by radicals can contribute much more than ionic anisotropy to the height of the reversal barrier of magnetization for the single-chain magnets (SCMs) with |2E| < |4J/3|. In addition, the anisotropic energy barrier ΔA decreases with the decrease of |2E/J| ratio and finally vanishes in the limit of broad domain walls (|2E| < < |4 J/3|). Therefore, the total magnetic relaxation energy barriers of two SCMs mostly originate from the correlation energy barrier Δξ deriving from the indirect ferromagnetic interaction between CoII–CoII transmitted by the strong CoII–radical antiferromagnetic interactions.

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“…Both SMMs and SCMs are of great interest because of their unusual physical properties, and their potential use in information storage at the molecular level and as qubits in quantum computation [7]. There are now many 3d-metal SMMs [8], but the number of SCMs is still relatively small [9], even though the first one was discovered many years ago [10]. Of the currently known examples, the majority are heterospin systems containing at least two different spin carriers bridged by organic radicals [10,11], oximate [12] or Prussian blue anions and derivatives [13], and obtained by a direct approach, using SMMs as building blocks.…”

Section: Introductionmentioning

confidence: 99%

‘Metal Complexes as Ligands’ for the Synthesis of Coordination Polymers: A MnIII Monomer as a Building Block for the Preparation of an Unprecedented 1-D {MnIIMnIII}n Linear Chain

et al. 2020

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A relatively unexplored synthetic route in redox-active Mn(II/III) coordination chemistry has been employed toward the preparation of a new mixed-valence MnII/III 1-D linear chain from the reaction of [MnIII(sacb)2]− precursor with a MnII source, where sacbH2 is the Schiff base ligand N-salicylidene-2-amino-5-chlorobenzoic acid. The mononuclear (Pr2NH2)[MnIII(sacb)2] (1) compound was obtained in excellent yields (>85%) from the 1:2:3 reaction of Mn(O2CMe)2∙4H2O, sacbH2 and Pr2NH, respectively. In 1, the two doubly deprotonated sacb2− ligands act as Ocarboxylate,Nimine,Ophenoxide-tridentate chelates, while the second carboxylate O atom of sacb2− is dangling and H-bonded to the Pr2NH2+ countercation. Complex 1 was subsequently used as a ‘ligand’ to react stoichiometrically with the ‘metal’ Mn(NO3)2∙4H2O, thus leading to the 1-D coordination polymer {[MnIIMnIII(sacb)2(H2O)2(MeOH)2](NO3)}n (2) in good yields (~50%). The removal of Pr2NH2+ from the vicinity of the [MnIII(sacb)2]− metalloligand has rendered possible (vide infra) the coordination of the second Ocarboxylate of sacb2− to neighboring {MnII(H2O)2(MeOH)2}2+ units, and consequently the formation of the 1-D polymer 2. Direct-current (dc) magnetic susceptibility studies revealed the presence of very weak antiferromagnetic exchange interactions between alternating MnIII and MnII atoms with a coupling constant of J = −0.08 cm−1 for g = 2.00. The combined results demonstrate the potential of the ‘metal complexes as ligands’ approach to yield new mixed-valence Mn(II/III) coordination polymers with interesting structural motifs and physicochemical properties.

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Single‐Chain Magnets

Cited by 21 publications

References 92 publications

Coercive Fields Above 6 T in Two Cobalt(II)–Radical Chain Compounds

Coercive Fields Above 6 T in Two Cobalt(II)–Radical Chain Compounds

Origin of Magnetic Relaxation Barriers in a Family of Cobalt(II)–Radical Single-Chain Magnets: Density Functional Theory and Ab Initio Calculations

‘Metal Complexes as Ligands’ for the Synthesis of Coordination Polymers: A MnIII Monomer as a Building Block for the Preparation of an Unprecedented 1-D {MnIIMnIII}n Linear Chain

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