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

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.

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

2021 ◽  
Vol 12 (14) ◽  
pp. 5134-5142 ◽  
Author(s):  
Aaron J. Scott ◽  
Julia Vallejo ◽  
Arup Sarkar ◽  
Lucy Smythe ◽  
E. Regincós Martí ◽  
...  
Keyword(s):  
Exchange Interactions ◽  
Magnetic Interactions ◽  
Magnetic Exchange ◽  
Guest Chemistry

The tetrahedral [NiII4L6]8+ cage can reversibly bind paramagnetic MX41/2− guests, inducing magnetic exchange interactions between host and guest.

Interplay between spin crossover and exchange interaction in iron(III) complexes

2009 ◽  
Vol 81 (8) ◽  
pp. 1357-1383 ◽  
Author(s):  
Roman Boča ◽  
Ivan Nemec ◽  
Ivan Šalitroš ◽  
Ján Pavlik ◽  
Radovan Herchel ◽  
...  
Keyword(s):  
Experimental Data ◽  
Magnetic Susceptibility ◽  
Exchange Interaction ◽  
Spin Crossover ◽  
Magnetic Measurements ◽  
Spin States ◽  
Magnetic Exchange Interaction ◽  
Magnetic Exchange ◽  
Simultaneous Fitting ◽  
Polynuclear Metal Complexes

In the dinuclear and polynuclear metal complexes exhibiting the low-spin (LS) to high-spin (HS) transition, the spin-crossover phenomenon interferes with the magnetic exchange interaction. The latter manifests itself in forming spin-multiplets, which causes a possible overlap of the band originating in different reference spin states (LL, LH, HL, and HH). A series of dinuclear Fe(III) complexes has been prepared; the iron centers are linked by a bidentate bridge (CN-, and diamagnetic metallacyanates {Fe(CN)5(NO)}, {Ni(CN)4}, {Pt(CN)4}, and {Ag(CN)2}). Magnetic measurements confirm that the spin crossover proceeds on the thermal propagation. This information has been completed also by the Mössbauer spectral (MS) data. A theoretical model has been developed that allows a simultaneous fitting of all available experimental data (magnetic susceptibility, magnetization, HS mole fraction) on a common set of parameters.

scholarly journals Structural and Magnetic Properties of Mn-Based Diluted Magnetic Semiconductors and Alloys

2009 ◽  
Vol 2009 ◽  
pp. 1-4 ◽  
Author(s):  
A. Alsaad
Keyword(s):  
Rock Salt ◽  
Diluted Magnetic Semiconductors ◽  
Magnetic Semiconductors ◽  
Exchange Interactions ◽  
Magnetic Interactions ◽  
Local Spin Density Approximation ◽  
Energy Minimum ◽  
Rock Salt Structure ◽  
Magnetic Exchange ◽  
Salt Structure

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.

Half-Integer Spin Molecular Nanomagnets

2002 ◽  
Vol 746 ◽  
Author(s):  
David N. Hendrickson ◽  
George Christou ◽  
Wolfgang Wernsdorfer ◽  
Stephen O. Hill ◽  
Núria Aliaga-Alcade ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Exchange Interaction ◽  
Single Molecule ◽  
Ground State ◽  
Exchange Interactions ◽  
Transverse Component ◽  
Zero Field ◽  
Magnetic Exchange ◽  
Integer Spin ◽  
Half Integer

ABSTRACTSingle-molecule magnets (SMM) are molecules that function as single-domain nanomagnets. SMMs have been characterized with a ground-state spin ranging from S = 4 to S = 13. A few SMMs have been identified that have half-integer spin ground states. [Cation][Mn12O12(O2CR)16(H2O)4] complexes, where R is some substituent, are SMMs that have either a S = 19/2 or 21/2 ground state. Quantum tunneling of magnetization (QTM) is observed for these half-integer-spin Kramers [Mn12]- degenerate SMMs in zero external magnetic field, as well as for a class of S = 9/2 Mn4 SMMs. The presence of QTM in zero external field is attributed to a transverse component of a nuclear spin field, dipolar interactions and intermolecular exchange interactions. The Landau-Zener method is used to measure the tunnel splitting as a function of transverse magnetic field for a single crystal of the S = 9/2 SMM [Mn4O3(OSiMe3)(OAc)3(dbm)3]. Spin parity dependent QTM is established. The effect of a magnetic exchange interaction between two S = 9/2 Mn4 SMMs upon QTM was studied for another compound. The hydrogen bonding and Cl…Cl contacts within a supramolecularly linked [Mn4]2 dimer lead to a weak antiferromagnetic exchange interaction between the two S = 9/2 SMMs. This interaction causes a shift (exchange bias) from zero field for the magnetic field at which QTM occurs.

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

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

<p>Reaction of Ni(OTf)<sub>2</sub> with the bisbidentate quaterpyridine ligand L results in the self-assembly of a tetrahedral, paramagnetic cage [Ni<sup>II</sup><sub>4</sub>L<sub>6</sub>]<sup>8+</sup>. By selectively exchanging the bound triflate from [OTfÌNi<sup>II</sup><sub>4</sub>L<sub>6</sub>](OTf)<sub>7</sub> (<b>1</b>), we have been able to prepare a series of host-guest complexes that feature an encapsulated paramagnetic tetrahalometallate ion inside this paramagnetic host giving [M<sup>II</sup>X<sub>4</sub>ÌNi<sup>II</sup><sub>4</sub>L<sub>6</sub>](OTf)<sub>6</sub>, where M<sup>II</sup>X<sub>4</sub><sup>2− </sup>= MnCl<sub>4</sub><sup>2−</sup> (<b>2</b>), CoCl<sub>4</sub><sup>2−</sup> (<b>5</b>), CoBr<sub>4</sub><sup>2−</sup> (<b>6</b>), NiCl<sub>4</sub><sup>2−</sup> (<b>7</b>), CuBr<sub>4</sub><sup>2−</sup> (<b>8</b>) or [M<sup>III</sup>X<sub>4</sub>ÌNi<sup>II</sup><sub>4</sub>L<sub>6</sub>](OTf)<sub>7</sub>, where M<sup>III</sup>X<sub>4</sub><sup>−</sup> = FeCl<sub>4</sub><sup>−</sup> (<b>3</b>), FeBr<sub>4</sub><sup>−</sup> (<b>4</b>). Triflate-to-tetrahalometallate exchange occurs in solution and can also be accomplished through single-crystal-to-single-crystal transformations. Host-guest complexes <b>1</b>-<b>8</b> all crystallise as homochiral racemates in monoclinic space groups, wherein the four {NiN<sub>6</sub>} vertex within a single Ni<sub>4</sub>L<sub>6</sub> unit possess the same Δ or Λ stereochemistry. Magnetic susceptibility and magnetisation data show that the magnetic exchange between metal ions in the host [Ni<sup>II</sup><sub>4</sub>] complex, and between the host and the MX<sub>4</sub><sup>n-</sup> 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 {MX<sub>4</sub>}<sup>n−</sup> guest molecules leads to stronger host-guest magnetic exchange interactions. </p>

scholarly journals Low-field Magnetic Anisotropy of Sr2IrO4

2022 ◽  
Author(s):  
Muhammad Nauman ◽  
Tayyaba Hussain ◽  
Joonyoung Choi ◽  
Nara Lee ◽  
Young Jai Choi ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Exchange Interaction ◽  
Exchange Interactions ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Easy Magnetization ◽  
Magnetic Exchange ◽  
Crystal Field Effect ◽  
Out Of Plane

Abstract Magnetic anisotropy in strontium iridate (Sr2IrO4) is essential because of its strong spin–orbit coupling and crystal field effect. In this paper, we present a detailed mapping of the out-of-plane (OOP) magnetic anisotropy in Sr2IrO4 for different sample orientations using torque magnetometry measurements in the low-magnetic-field region before the isospins are completely ordered. Dominant in-plane anisotropy was identified at low fields, confirming the b axis as an easy magnetization axis. Based on the fitting analysis of the strong uniaxial magnetic anisotropy, we observed that the main anisotropic effect arises from a spin–orbit-coupled magnetic exchange interaction affecting the OOP interaction. The effect of interlayer exchange interaction results in additional anisotropic terms owing to the tilting of the isospins. The results are relevant for understanding OOP magnetic anisotropy and provide a new way to analyze the effects of spin–orbit-coupling and interlayer magnetic exchange interactions. This study provides insight into the understanding of bulk magnetic, magnetotransport, and spintronic behavior on Sr2IrO4 for future studies.

scholarly journals Synthesis, Structural Features and Physical Properties of a Family of Triply Bridged Dinuclear 3d-4f Complexes

2021 ◽  
Vol 7 (2) ◽  
pp. 22
Author(s):  
Itziar Oyarzabal ◽  
Estitxu Echenique-Errandonea ◽  
Eider San Sebastián ◽  
Antonio Rodríguez-Diéguez ◽  
José Manuel Seco ◽  
...  
Keyword(s):  
Metal Ions ◽  
Density Functional ◽  
Magnetic Measurements ◽  
Theoretical Calculations ◽  
Exchange Interactions ◽  
Transition Metal Ions ◽  
Structural Features ◽  
Coupling Constants ◽  
Metallic Ions ◽  
Magnetic Exchange

New dinuclear MII-LnIII complexes of general formulas [Cu(µ-L)(µ-OAc)Ln(NO3)2]·CH3CN·H2O (LnIII = Gd (1), Tb (2), Dy (3) and Er (4)), [Ni(CH3CN)(µ-L)(µ-OAc)Ln(NO3)2]·CH3CN (LnIII = Nd (5), Gd (6), Tb (7), Dy (8), Er (9) and Y (10)) and [Co(CH3CN)(µ-L)(µ-OAc)Ln(NO3)2]·CH3CN (LnIII = Gd (11), Tb (12), Dy (13), Er (14) and Y (15)) were prepared from the compartmental ligand N,N′-dimethyl-N,N′-bis(2-hydroxy-3-formyl-5-bromo-benzyl)ethylenediamine (H2L). In all these complexes, the transition metal ions occupy the internal N2O2 coordination site of the ligand, whereas the LnIII ions lie in the O4 external site. Both metallic ions are connected by an acetate bridge, giving rise to triple mixed diphenoxido/acetate bridged MIILnIII compounds. Direct current (dc) magnetic measurements allow the study of the magnetic exchange interactions between the 3d and 4f metal ions, which is supported by density functional theory (DFT) theoretical calculations for the GdIII-based counterparts. Due to the weak ferromagnetic exchange coupling constants obtained both experimentally and theoretically, the magneto-thermal properties of the less anisotropic systems (compounds 1 and 6) are also studied. Alternating current (ac)magnetic measurements reveal the occurrence of slight frequency dependency of the out-of-phase signal for complexes 8, 9 and 13, while complex 15 displays well-defined maximums below ~6 K.

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

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.

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

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.

Ion - Carrier Exchange Interaction in Cd1−xMnxS

1986 ◽  
Vol 89 ◽  
Author(s):  
M. Nawrocki ◽  
J. P. Lascaray ◽  
D. Coquillat ◽  
M. Demianiuk
Keyword(s):  
Magnetic Field ◽  
Exchange Interaction ◽  
Valence Band ◽  
Field Model ◽  
Free Exciton ◽  
Mean Field ◽  
Exchange Integral ◽  
Mean Field Model ◽  
Exciton Region ◽  
Type Crystal

AbstractMagnetoreflectivity measurements in Faraday and Voigt geometry in the free exciton region (A, B and C excitons are visible) were performed on Cd0.07Mn0.13S at T=1.6 K for magnetic field up to 5.5 T. An analysis of the results in terms of a mean field model for wurtzite type crystal enabled to determine band parameters Δ1, Δ2, Δ3 and exchange integral for valence band N0ß = -1.8 ± 0.08 eV

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