Mean Field Analysis of the Exchange Coupling (<i>J</i>) for Two- and Three-Dimensional Structured Tetracyanoethenide (TCNE<sup>•–</sup>)-Based Magnets

McConnell, Amber C.; Fishman, Randy Scott; Miller, Joel S.

doi:10.1021/jp302765d

Cited by 9 publications

(13 citation statements)

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“…Note that K can be estimated from the critical field, H c {= |K| S 2 /[μ B (S − S′)]}, for the spin-flop transition. 16 Since the spin flop transition is not observed 8 up to 9 T, |K|/k B > 3.8 K, which is consistent with the estimate of K/k B = −6.7 K above. The spin-flop field for that value of K would be ∼14 T.…”

Section: ■ Estimation Of Exchange Coupling Jsupporting

confidence: 89%

A Mean-Field Analysis of the Exchange Coupling (J) for Noncubic Prussian Blue Analogue Magnets

et al. 2012

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Mean field expressions based on the simple Heisenberg model were derived to correlate the intra- and interlayer exchange couplings to the critical temperatures, T c, for three metallocyanide-based magnets with extended 2- and 3-D structure types. These expressions were used to estimate the exchange coupling, J, for 2-D ferrimagnetic [NEt4]2MnII 3(CN)8, 3-D antiferromagnetic [NEt4]MnII 3(CN)7, and 3-D antiferromagnetic interpenetrating 3-D MnII(CN)2. The type and magnitude of the exchange coupling are in accord with the previously reported magnetic data.

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Section: ■ Estimation Of Exchange Coupling Jsupporting

confidence: 89%

A Mean-Field Analysis of the Exchange Coupling (J) for Noncubic Prussian Blue Analogue Magnets

et al. 2012

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“…Recently, Mn II (TCNE)[C 4 (CN) 8 ] 1/2 · z CH 2 Cl 2 was reported to have an antiferromagnetic ground state . It has corrugated layers of Mn II ions bonded to four S = 1 / 2 μ 4 -[TCNE] •– , and these layers are bridged by the diamagnetic ( S = 0) μ 4 -[C 4 (CN) 8 ] 2– dimer (Figure ).…”

Section: Introductionmentioning

confidence: 99%

Pressure-Induced Transition from an Antiferromagnet to a Ferrimagnet for Mn^II(TCNE)[C₄(CN)₈]_1/2 (TCNE = Tetracyanoethylene)

2012

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Mn(II)(TCNE)[C(4)(CN)(8)](1/2) (TCNE = tetracyanoethylene) exhibits a reversible pressure-induced piezomagnetic transition from a low magnetization antiferromagnetic state to a high magnetization ferrimagnetic state above 0.50 ± 0.15 kbar. In the ferrimagnetic state, the critical temperature, T(c), increases with increasing hydrostatic pressure and is ~97 K at 12.6 kbar, the magnetization increases by 3 orders of magnitude (1000-fold), and the material becomes a hard magnet with a significant remnant magnetization.

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“…53 Using DFT-calculated J values for the compounds 2D and 3D and the structures' corresponding T c expressions, 53 the corresponding critical temperature values of T c 2D ∼ 941 K and T c 3D ∼ 1690 K have been derived. The estimated values exceed those obtained experimentally by about an order of magnitude.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Recently mean-field formulas based on the simple Heisenberg model were proposed, thus allowing the correlation of inter-and intralayer exchange coupling to the critical temperature, T c , for several M [TCNE] MBMs with extended 2-D and 3-D structures. 53 Using DFT-calculated J values for the compounds 2D and 3D and the structures' corresponding T c expressions, 53 the corresponding critical temperature values of T c 2D ∼ 941 K and T c 3D ∼ 1690 K have been derived. The estimated values exceed those obtained experimentally by about an order of magnitude.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Recently mean-field formulas based on the simple Heisenberg model were proposed, thus allowing the correlation of inter- and intralayer exchange coupling to the critical temperature, T c , for several M[TCNE] MBMs with extended 2-D and 3-D structures . Using DFT-calculated J values for the compounds 2D and 3D and the structures’ corresponding T c expressions, the corresponding critical temperature values of T c 2D ∼ 941 K and T c 3D ∼ 1690 K have been derived. The estimated values exceed those obtained experimentally by about an order of magnitude. , The discrepancy likely occurs due to overlooked thermal fluctuations and the possible FM exchange channels involving Mn 3d-e g derived electrons that may weaken kinetic exchange resulting in lower T c …”

Section: Resultsmentioning

confidence: 99%

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Magnetic Exchange in Mn^II[TCNE] (TCNE = Tetracyanoethylene) Molecule-Based Magnets with Two- and Three-Dimensional Magnetic Networks

Olson

Gangopadhyay²,

Hoang³

et al. 2015

J. Phys. Chem. C

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The chemical bond and its role as a mediator of magnetic exchange interaction remains a crucial aspect in the study of molecular magnetism. Within the M[TCNE] (M = 3d metal; TCNE = tetracyanoethylene) class of organic-based magnets, only V [TCNE] x (x ∼ 2) orders magnetically above room temperature (T c ∼ 400 K), while structural factors underlying this exceptional behavior remain elusive. Conversely, Mn-[TCNE] complexes of diverse crystal structure have recently become available, e.g., 2D-layer [Mn(TCNE)(NCMe) 2 ][SbF 6 ] (T c ∼ 75 K), and 3D-network [Mn(TCNE) 1.5 ](I 3 ) 0.5 (T c ∼ 170 K). Using this experimental structural data, DFT simulations have been performed and the spin-polarized electronic structures resolved. The nature of orbital interactions crucial for understanding magnetic behavior was revealed. Magnetic coupling, spin−orbital hybridization, as well as formation of exchange/superexchange pathways have been identified and interpreted in terms of the dimensionality of magnetic interaction. These results illustrate the complex nature of the electron exchange landscape in M[TCNE] molecule-based magnets. ■ INTRODUCTIONFor several decades, magnetism in the solids containing 3d electrons has remained one of the main focuses of modern materials science targeting applications in spintronics. In contrast to the itinerant ferromagnetic exchange between almost free electrons in metals (direct exchange), the main mechanism of exchange interaction in magnetic insulators like simple transition metal oxides is a virtual hopping of electrons between almost isolated ions (metal and oxygen) leading either to anti-or ferromagnetic Heisenberg exchange interaction between unpaired spins of metals, traditionally defined as indirect-or superexchange. 1−3Molecule-based magnets (MBMs) are a relatively new class of magnetic materials, in which molecular moieties bearing unpaired spin density interact electronically and magnetically. 4,5 Compared to conventional metallurgic and ceramic magnets, the main benefits of MBMs are usually associated with their lightweight, mechanical flexibility, tunable color or transparency, low-temperature processing, solubility, and compatibility with polymers and other classes of molecular materials. 6 Furthermore, the use of MBMs in the area of spintronics has the potential to become a disruptive technology, since organic materials can enhance preservation of electron spin orientation lifetime relative to inorganic conductors due to their inherently weak spin−orbit coupling. The M[TCNE] (M = 3d metal; TCNE = tetracyanoethylene) complexes represent one of the most interesting classes of MBMs, possessing numerous compositions and structures with varying dimensionalities of magnetic coupling from one-dimensional (1D) inorganic polymer chains 7 and two-dimensional (2D) layers 8−10 to three-dimensional (3D) networks 11 and amorphous solids. 12 M[TCNE] MBMs exhibit a wide range of magnetic ordering temperatures (T c ), with the highest of 400 K observed in V[TCNE] x (x ∼ 2). 12 Recently, interest...

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Mean Field Analysis of the Exchange Coupling (J) for Two- and Three-Dimensional Structured Tetracyanoethenide (TCNE^•–)-Based Magnets

Cited by 9 publications

References 45 publications

A Mean-Field Analysis of the Exchange Coupling (J) for Noncubic Prussian Blue Analogue Magnets

A Mean-Field Analysis of the Exchange Coupling (J) for Noncubic Prussian Blue Analogue Magnets

Pressure-Induced Transition from an Antiferromagnet to a Ferrimagnet for Mn^II(TCNE)[C₄(CN)₈]_1/2 (TCNE = Tetracyanoethylene)

Magnetic Exchange in Mn^II[TCNE] (TCNE = Tetracyanoethylene) Molecule-Based Magnets with Two- and Three-Dimensional Magnetic Networks

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Mean Field Analysis of the Exchange Coupling (J) for Two- and Three-Dimensional Structured Tetracyanoethenide (TCNE•–)-Based Magnets

Cited by 9 publications

References 45 publications

A Mean-Field Analysis of the Exchange Coupling (J) for Noncubic Prussian Blue Analogue Magnets

A Mean-Field Analysis of the Exchange Coupling (J) for Noncubic Prussian Blue Analogue Magnets

Pressure-Induced Transition from an Antiferromagnet to a Ferrimagnet for MnII(TCNE)[C4(CN)8]1/2 (TCNE = Tetracyanoethylene)

Magnetic Exchange in MnII[TCNE] (TCNE = Tetracyanoethylene) Molecule-Based Magnets with Two- and Three-Dimensional Magnetic Networks

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Product

Resources

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Mean Field Analysis of the Exchange Coupling (J) for Two- and Three-Dimensional Structured Tetracyanoethenide (TCNE^•–)-Based Magnets

Pressure-Induced Transition from an Antiferromagnet to a Ferrimagnet for Mn^II(TCNE)[C₄(CN)₈]_1/2 (TCNE = Tetracyanoethylene)

Magnetic Exchange in Mn^II[TCNE] (TCNE = Tetracyanoethylene) Molecule-Based Magnets with Two- and Three-Dimensional Magnetic Networks