Exploiting host–guest chemistry to manipulate magnetic interactions in metallosupramolecular M4L6 tetrahedral cages

Direct supercell approach calculations of the magnetic exchange interactions in Mn-doped ScN was carried out in the local spin density approximation by using the muffin-tin-orbital Green's function method. We found that magnetic interactions are long range interactions and affected by the randomness, band gap corrections, and carrier concentrations. Using total energy minimization approach we found that the global energy minimum of MnN is obtained for zinc-blende structure. If the compound is compressed by 6%, the energy minimum corresponds to the rock-salt structure in disagreement with the experimentally observed tetragonal distorted rock-salt structure, known as -phase. An isostructural phase transition for alloys from MnN -phase to -ScN phase was found to occur at a hydrostatic pressure of 18 GPa. We predict above room temperature for Mn concentrations of about 10% in ScN : Mn system.

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Exploiting Host-Guest Chemistry to Manipulate Magnetic Interactions in Metallosupramolecular M4L6 Tetrahedral Cages

10.26434/chemrxiv.13720849.v1 ◽

2021 ◽

Author(s):

Aaron Scott ◽

Julia Vallejo ◽

Arup Sarkar ◽

Lucy Smythe ◽

Emma Regincós Martí ◽

...

Keyword(s):

Single Crystal ◽

Self Assembly ◽

Close Agreement ◽

Exchange Interactions ◽

Magnetic Interactions ◽

Magnetic Exchange ◽

Guest Molecules ◽

Space Groups ◽

Comparable Magnitude ◽

Spin Densities

Reaction of Ni(OTf)2 with the bisbidentate quaterpyridine ligand L results in the self-assembly of a tetrahedral, paramagnetic cage [NiII4L6]8+. By selectively exchanging the bound triflate from [OTfÌNiII4L6](OTf)7 (1), we have been able to prepare a series of host-guest complexes that feature an encapsulated paramagnetic tetrahalometallate ion inside this paramagnetic host giving [MIIX4ÌNiII4L6](OTf)6, where MIIX42− = MnCl42− (2), CoCl42− (5), CoBr42− (6), NiCl42− (7), CuBr42− (8) or [MIIIX4ÌNiII4L6](OTf)7, where MIIIX4− = FeCl4− (3), FeBr4− (4). Triflate-to-tetrahalometallate exchange occurs in solution and can also be accomplished through single-crystal-to-single-crystal transformations. Host-guest complexes 1-8 all crystallise as homochiral racemates in monoclinic space groups, wherein the four {NiN6} vertex within a single Ni4L6 unit possess the same Δ or Λ stereochemistry. Magnetic susceptibility and magnetisation data show that the magnetic exchange between metal ions in the host [NiII4] complex, and between the host and the MX4n- guest, are of comparable magnitude and antiferromagnetic in nature. Theoretically derived values for the magnetic exchange are in close agreement with experiment, revealing that large spin densities on the electronegative X-atoms of particular {MX4}n− guest molecules leads to stronger host-guest magnetic exchange interactions.

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Determining the range of magnetic interactions from the relations between magnon eigenvalues at high-symmetry k points

10.21203/rs.3.rs-334283/v1 ◽

2021 ◽

Author(s):

Di Wang ◽

Jihai Yu ◽

Feng Tang ◽

Yuan Li ◽

Xiangang Wan

Keyword(s):

Magnetic Moments ◽

A Priori ◽

Exchange Interactions ◽

Wave Theory ◽

Real Space ◽

Simple Relation ◽

Magnetic Interactions ◽

High Symmetry ◽

Magnetic Exchange ◽

The Fourier Transform

Abstract Magnetic exchange interactions (MEIs) define networks of coupled magnetic moments and lead to a surprisingly rich variety of their magnetic properties. Typically MEIs can be estimated by fitting experimental results. But how many MEIs need to be included in the fitting process for a material is not clear a priori, which limits the quality of results obtained by these conventional methods. In this paper, based on linear spin-wave theory but without performing matrix diagonalization, we show that for a general quadratic spin Hamiltonian, there is a simple relation between the Fourier transform of MEIs and the sum of square of magnon energies (SSME). We further show that according to the real-space distance range within which MEIs are considered relevant, one can obtain the corresponding relationships between SSME in momentum space. We also develop a theoretical tool for tabulating the rule about SSME. By directly utilizing these characteristics and the experimental magnon energies at only a few high-symmetry k points in the Brillouin zone, one can obtain strong constraints about the range of exchange path beyond which MEIs can be safely neglected. Our methodology is also general applicable for other Hamiltonian with quadratic Fermi or Boson operators.

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Exploiting Host-Guest Chemistry to Manipulate Magnetic Interactions in Metallosupramolecular M4L6 Tetrahedral Cages

10.26434/chemrxiv.13720849 ◽

2021 ◽

Author(s):

Aaron Scott ◽

Julia Vallejo ◽

Arup Sarkar ◽

Lucy Smythe ◽

Emma Regincós Martí ◽

...

Keyword(s):

Single Crystal ◽

Self Assembly ◽

Close Agreement ◽

Exchange Interactions ◽

Magnetic Interactions ◽

Magnetic Exchange ◽

Guest Molecules ◽

Space Groups ◽

Comparable Magnitude ◽

Spin Densities

Reaction of Ni(OTf)2 with the bisbidentate quaterpyridine ligand L results in the self-assembly of a tetrahedral, paramagnetic cage [NiII4L6]8+. By selectively exchanging the bound triflate from [OTfÌNiII4L6](OTf)7 (1), we have been able to prepare a series of host-guest complexes that feature an encapsulated paramagnetic tetrahalometallate ion inside this paramagnetic host giving [MIIX4ÌNiII4L6](OTf)6, where MIIX42− = MnCl42− (2), CoCl42− (5), CoBr42− (6), NiCl42− (7), CuBr42− (8) or [MIIIX4ÌNiII4L6](OTf)7, where MIIIX4− = FeCl4− (3), FeBr4− (4). Triflate-to-tetrahalometallate exchange occurs in solution and can also be accomplished through single-crystal-to-single-crystal transformations. Host-guest complexes 1-8 all crystallise as homochiral racemates in monoclinic space groups, wherein the four {NiN6} vertex within a single Ni4L6 unit possess the same Δ or Λ stereochemistry. Magnetic susceptibility and magnetisation data show that the magnetic exchange between metal ions in the host [NiII4] complex, and between the host and the MX4n- guest, are of comparable magnitude and antiferromagnetic in nature. Theoretically derived values for the magnetic exchange are in close agreement with experiment, revealing that large spin densities on the electronegative X-atoms of particular {MX4}n− guest molecules leads to stronger host-guest magnetic exchange interactions.

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Determination of the Range of Magnetic Interactions from the Relations between Magnon Eigenvalues at High-Symmetry κ Points

Chinese Physics Letters ◽

10.1088/0256-307x/38/11/117101 ◽

2021 ◽

Vol 38 (11) ◽

pp. 117101

Author(s):

Di Wang ◽

Jihai Yu ◽

Feng Tang ◽

Yuan Li ◽

Xiangang Wan

Keyword(s):

Magnetic Moments ◽

A Priori ◽

Exchange Interactions ◽

Wave Theory ◽

Real Space ◽

Simple Relation ◽

Magnetic Interactions ◽

High Symmetry ◽

Magnetic Exchange ◽

The Fourier Transform

Magnetic exchange interactions (MEIs) define networks of coupled magnetic moments and lead to a surprisingly rich variety of their magnetic properties. Typically MEIs can be estimated by fitting experimental results. Unfortunately, how many MEIs need to be included in the fitting process for a material is unclear a priori, which limits the results obtained by these conventional methods. Based on linear spin-wave theory but without performing matrix diagonalization, we show that for a general quadratic spin Hamiltonian, there is a simple relation between the Fourier transform of MEIs and the sum of square of magnon energies (SSME). We further show that according to the real-space distance range within which MEIs are considered relevant, one can obtain the corresponding relationships between SSME in momentum space. By directly utilizing these characteristics and the experimental magnon energies at only a few high-symmetry k points in the Brillouin zone, one can obtain strong constraints about the range of exchange path beyond which MEIs can be safely neglected. Our methodology is also generally applicable for other Hamiltonian with quadratic Fermi or Boson operators.

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Magnetic Exchange Interactions and Supertransferred Hyperfine Fields at 119Sn Probe Atoms in CaCu3Mn4O12 Manganite

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.190.695 ◽

2012 ◽

Vol 190 ◽

pp. 695-698

Author(s):

V.S. Rusakov ◽

I.A. Presniakov ◽

A.V. Sobolev ◽

Gérard Demazeau ◽

A.M. Gapochka ◽

...

Keyword(s):

Exchange Interaction ◽

Field Model ◽

Magnetic Measurements ◽

Exchange Interactions ◽

Local Environment ◽

Electronic Configuration ◽

Magnetic Interactions ◽

Exchange Integral ◽

Hyperfine Fields ◽

Magnetic Exchange

The hyperfine magnetic interactions of 119Sn probe atoms in the CaCu3Mn3.96Sn0.04O12 double manganite by Mössbauer spectroscopy using magnetic measurements have been investigated. A consistent description of the results obtained in terms of the Weiss molecular field model by taking into account the peculiarities of the local environment of tin atoms has allowed the indirect Cu2+OMn4+ (JCuMn 51 ± 1 K) and Mn4+OMn4+ (JMnMn 0.6 ± 0.6 K) exchange interaction integrals to be estimated. Based on the KanamoriGoodenoughAnderson model, we show that the magnitude and sign of the intrasublattice exchange integral JMnMn correspond to both the electronic configuration of the Mn4+ cations and the geometry of their local crystallographic environment in the compound under study.

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A new 1-1-4 pattern of magnetic exchange interactions in a cubane core tetranuclear copper (II) complex

Polyhedron ◽

10.1016/j.poly.2021.115088 ◽

2021 ◽

Vol 199 ◽

pp. 115088

Author(s):

Azadeh Mehrani ◽

Maurice G. Sorolla ◽

Tatyana Makarenko ◽

Allan J. Jacobson

Keyword(s):

Exchange Interactions ◽

Magnetic Exchange

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Isotropic Nature of the Metallic Kagome Ferromagnet Fe3Sn2 at High Temperatures

Crystals ◽

10.3390/cryst11030307 ◽

2021 ◽

Vol 11 (3) ◽

pp. 307

Author(s):

Rebecca L. Dally ◽

Daniel Phelan ◽

Nicholas Bishop ◽

Nirmal J. Ghimire ◽

Jeffrey W. Lynn

Keyword(s):

Elevated Temperatures ◽

Magnetocrystalline Anisotropy ◽

Inelastic Neutron Scattering ◽

Exchange Interactions ◽

Inelastic Neutron ◽

Temperature Threshold ◽

Magnetic Exchange ◽

Spatial Anisotropy ◽

Isotropic Exchange ◽

State Spin

Anisotropy and competing exchange interactions have emerged as two central ingredients needed for centrosymmetric materials to exhibit topological spin textures. Fe3Sn2 is thought to have these ingredients as well, as it has recently been discovered to host room temperature skyrmionic bubbles with an accompanying topological Hall effect. We present small-angle inelastic neutron scattering measurements that unambiguously show that Fe3Sn2 is an isotropic ferromagnet below TC≈660 K to at least 480 K—the lower temperature threshold of our experimental configuration. Fe3Sn2 is known to have competing magnetic exchange interactions, correlated electron behavior, weak magnetocrystalline anisotropy, and lattice (spatial) anisotropy; all of these features are thought to play a role in stabilizing skyrmions in centrosymmetric systems. Our results reveal that at the elevated temperatures measured, there is an absence of significant magnetocrystalline anisotropy and that the system behaves as a nearly ideal isotropic exchange interaction ferromagnet, with a spin stiffness D(T=480 K)=168 meV Å2, which extrapolates to a ground state spin stiffness D(T=0 K)=231 meV Å2.

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