Role of Magnetic Exchange Interactions in the Magnetization Relaxation of {3d-4f} Single-Molecule Magnets: A Theoretical Perspective

2015 ◽  
Vol 22 (2) ◽  
pp. 672-680 ◽  
Author(s):  
Saurabh Kumar Singh ◽  
Mohammad Faizan Beg ◽  
Gopalan Rajaraman
Keyword(s):  
Single Molecule ◽  
Theoretical Perspective ◽  
Exchange Interactions ◽  
Single Molecule Magnets ◽  
Magnetic Exchange ◽  
Magnetization Relaxation

scholarly journals Pseudo-Tetrahedral vs Pseudo-Octahedral ErIII Single Molecule Magnets and the 'Disruptive' Role of Coordinated TEMPO Radicals

2021 ◽  
Author(s):  
Maria Brzozowska ◽  
Gabriela Handzlik ◽  
Katarzyna Kurpiewska ◽  
Mikołaj Zychowicz ◽  
Dawid Pinkowicz
Keyword(s):  
Single Molecule ◽  
High Performance ◽  
Magnetic Hysteresis ◽  
Magnetic Hysteresis Loop ◽  
Relaxation Mechanism ◽  
Magnetic Memory ◽  
Single Molecule Magnets ◽  
Magnetization Relaxation ◽  
Tempo Radical

Erbium(III) complexes are the most interesting candidates for high-performance single molecule magnets (SMMs) just after dysprosium(III). Herein, we thoroughly explore the underrepresented class of neutral pseudo-tetrahedral erbium(III) SMMs and demonstrate their exceptional slow magnetization dynamics controlled by the Raman relaxation mechanism and the molecular magnetic memory effect in the form of a waist-restricted magnetic hysteresis loop. The influence of the coordinated TEMPO radical on the slow magnetization relaxation performance is also demonstrated and discussed.<br>

scholarly journals Asymmetric Dinuclear Lanthanide(III) Complexes from the Use of a Ligand Derived from 2-Acetylpyridine and Picolinoylhydrazide: Synthetic, Structural and Magnetic Studies

Molecules ◽  
2020 ◽  
Vol 25 (14) ◽  
pp. 3153
Author(s):  
Diamantoula Maniaki ◽  
Panagiota S. Perlepe ◽  
Evangelos Pilichos ◽  
Sotirios Christodoulou ◽  
Mathieu Rouzières ◽  
...  
Keyword(s):  
Single Molecule ◽  
Metal Ion ◽  
Ac Susceptibility ◽  
Solvent Molecule ◽  
Exchange Interactions ◽  
Experimental Fact ◽  
Anisotropy Axis ◽  
Magnetic Studies ◽  
Single Molecule Magnets ◽  
Magnetization Relaxation

A family of four Ln(III) complexes has been synthesized with the general formula [Ln2(NO3)4(L)2(S)] (Ln = Gd, Tb, Er, and S = H2O; 1, 2 and 4, respectively/Ln = Dy, S = MeOH, complex 3), where HL is the flexible ditopic ligand N’-(1-(pyridin-2-yl)ethylidene)pyridine-2-carbohydrazide. The structures of isostructural MeOH/H2O solvates of these complexes were determined by single-crystal X-ray diffraction. The two LnIII ions are doubly bridged by the deprotonated oxygen atoms of two “head-to-head” 2.21011 (Harris notation) L¯ ligands, forming a central, nearly rhombic {LnIII2(μ-OR)2}4+ core. Two bidentate chelating nitrato groups complete a sphenocoronal 10-coordination at one metal ion, while two bidentate chelating nitrato groups and one solvent molecule (H2O or MeOH) complete a spherical capped square antiprismatic 9-coordination at the other. The structures are critically compared with those of other, previously reported metal complexes of HL or L¯. The IR spectra of 1–4 are discussed in terms of the coordination modes of the organic and inorganic ligands involved. The f-f transitions in the solid-state (diffuse reflectance) spectra of the Tb(III), Dy(III), and Er(III) complexes have been fully assigned in the UV/Vis and near-IR regions. Magnetic susceptibility studies in the 1.85–300 K range reveal the presence of weak, intramolecular GdIII∙∙∙GdIII antiferromagnetic exchange interactions in 1 [J/kB = −0.020(6) K based on the spin Hamiltonian Ĥ = −2J(ŜGd1∙ ŜGd2)] and probably weak antiferromagnetic LnIII∙∙∙LnIII exchange interactions in 2–4. Ac susceptibility measurements in zero dc field do not show frequency dependent out-of-phase signals, and this experimental fact is discussed for 3 in terms of the magnetic anisotropy axis for each DyIII center and the oblate electron density of this metal ion. Complexes 3 and 4 are Single-Molecule Magnets (SMMs) and this behavior is optimally observed under external dc fields of 600 and 1000 Oe, respectively. The magnetization relaxation pathways are discussed and a satisfactory fit of the temperature and field dependencies of the relaxation time τ was achieved considering a model that employs Raman, direct, and Orbach relaxation mechanisms.

scholarly journals Pseudo-Tetrahedral vs Pseudo-Octahedral ErIII Single Molecule Magnets and the 'Disruptive' Role of Coordinated TEMPO Radicals

2021 ◽  
Author(s):  
Maria Brzozowska ◽  
Gabriela Handzlik ◽  
Katarzyna Kurpiewska ◽  
Mikołaj Zychowicz ◽  
Dawid Pinkowicz
Keyword(s):  
Single Molecule ◽  
High Performance ◽  
Magnetic Hysteresis ◽  
Magnetic Hysteresis Loop ◽  
Relaxation Mechanism ◽  
Magnetic Memory ◽  
Single Molecule Magnets ◽  
Magnetization Relaxation ◽  
Tempo Radical

Erbium(III) complexes are the most interesting candidates for high-performance single molecule magnets (SMMs) just after dysprosium(III). Herein, we thoroughly explore the underrepresented class of neutral pseudo-tetrahedral erbium(III) SMMs and demonstrate their exceptional slow magnetization dynamics controlled by the Raman relaxation mechanism and the molecular magnetic memory effect in the form of a waist-restricted magnetic hysteresis loop. The influence of the coordinated TEMPO radical on the slow magnetization relaxation performance is also demonstrated and discussed.<br>

scholarly journals Some new trends in the design of single molecule magnets

2017 ◽  
Vol 89 (8) ◽  
pp. 1119-1143 ◽  
Author(s):  
Sergey M. Aldoshin ◽  
Denis V. Korchagin ◽  
Andrew V. Palii ◽  
Boris S. Tsukerblat
Keyword(s):  
Magnetic Anisotropy ◽  
Metal Ions ◽  
Single Molecule ◽  
Exchange Interactions ◽  
Structural Factors ◽  
Single Molecule Magnets ◽  
Crystal Fields ◽  
Angular Momenta ◽  
Isotropic Exchange

AbstractIn this review we briefly discuss some new trends in the design of single molecule magnets based on transition (3d, 4d, 5d) and rare-earth (4f) metal ions. Within this broad theme the emphasis of the present review is placed on the molecules which exhibit strong magnetic anisotropy originating from the unquenched orbital angular momenta in the ground orbitally degenerate (or quasi-degenerate) states. Along with the general concepts we consider selected examples of the systems comprising orbitally-degenerate metal ions and demonstrate how one can benefit from strong single-ion anisotropy arising from the first-order orbital angular momentum. The role of crystal fields, spin-orbit coupling and structural factors is discussed. Some observation stemming from the analysis of the isotropic exchange interactions, magnetic anisotropy and strongly anisotropic orbitally-dependent superexchange are summarized as guiding rules for the controlled design of single molecule magnets exhibiting high barriers for magnetization reversal and, consequently, high blocking temperatures.

The localized electron: magnetic properties

2018 ◽  
Author(s):  
Jean-Pierre Launay ◽  
Michel Verdaguer
Keyword(s):  
Single Molecule ◽  
Model Systems ◽  
Ferromagnetic Coupling ◽  
Single Chain ◽  
Single Molecule Magnets ◽  
Magnetic Systems ◽  
Orbital Interactions ◽  
Prussian Blue Analogues ◽  
Mononuclear Complexes

After preliminaries about electron properties, and definitions in magnetism, one treats the magnetism of mononuclear complexes, in particular spin cross-over, showing the role of cooperativity and the sensitivity to external perturbations. Orbital interactions and exchange interaction are explained in binuclear model systems, using orbital overlap and orthogonality concepts to explain antiferromagnetic or ferromagnetic coupling. The phenomenologically useful Spin Hamiltonian is defined. The concepts are then applied to extended molecular magnetic systems, leading to molecular magnetic materials of various dimensionalities exhibiting bulk ferro- or ferrimagnetism. An illustration is provided by Prussian Blue analogues. Magnetic anisotropy is introduced. It is shown that in some cases, a slow relaxation of magnetization arises and gives rise to appealing single-ion magnets, single-molecule magnets or single-chain magnets, a route to store information at the molecular level.

scholarly journals High-Coordinate Mononuclear Ln(III) Complexes: Synthetic Strategies and Magnetic Properties

2020 ◽  
Vol 7 (1) ◽  
pp. 1
Author(s):  
Joydev Acharya ◽  
Pankaj Kalita ◽  
Vadapalli Chandrasekhar
Keyword(s):  
Magnetic Properties ◽  
Single Molecule ◽  
Fine Tuning ◽  
Coordination Geometry ◽  
Single Molecule Magnets ◽  
Magnetization Relaxation ◽  
Quantum Tunneling Of Magnetization ◽  
Structural Correlation ◽  
High Coordination Number ◽  
High Coordination

Single-molecule magnets involving monometallic 4f complexes have been investigated extensively in last two decades to understand the factors that govern the slow magnetization relaxation behavior in these complexes and to establish a magneto-structural correlation. The prime goal in this direction is to suppress the temperature independent quantum tunneling of magnetization (QTM) effect via fine-tuning the coordination geometry/microenvironment. Among the various coordination geometries that have been pursued, complexes containing high coordination number around Ln(III) are sparse. Herein, we present a summary of the various synthetic strategies that were used for the assembly of 10- and 12-coordinated Ln(III) complexes. The magnetic properties of such complexes are also described.

Single-Molecule Magnets:  Two-Electron Reduced Version of a Mn12Complex and Environmental Influences on the Magnetization Relaxation of (PPh4)2[Mn12O12(O2CCHCl2)16(H2O)4]

2003 ◽  
Vol 125 (12) ◽  
pp. 3576-3588 ◽  
Author(s):  
Monica Soler ◽  
Wolfgang Wernsdorfer ◽  
Khalil A. Abboud ◽  
John C. Huffman ◽  
Ernest R. Davidson ◽  
...  
Keyword(s):  
Single Molecule ◽  
Environmental Influences ◽  
Single Molecule Magnets ◽  
Magnetization Relaxation

scholarly journals Leveraging Surface Siloxide Electronics to Enhance Relaxation Properties of a Single-Molecule Magnet

2020 ◽  
Author(s):  
Maciej Korzynski ◽  
Zachariah Berkson ◽  
Boris Le Guennic ◽  
Olivier Cador ◽  
Christophe Copéret
Keyword(s):  
Single Molecule ◽  
Relaxation Times ◽  
Device Fabrication ◽  
Information Storage ◽  
Commercial Application ◽  
Surface Immobilization ◽  
Single Molecule Magnets ◽  
Magnetization Relaxation ◽  
Surface Deposition ◽  
Magnitude Increase

Single-molecule magnets (SMMs) hold promise for unmatched information storage density as well as applications in quantum computing and spintronics. To date, the most successful SMMs are organometallic lanthanide complexes. However, their surface immobilization, one of the requirements for device fabrication and commercial application, remains challenging due to sensitivity of magnetic properties to small changes in the electronic structure of the parent SMM. Thus, finding controlled approaches to SMM surface deposition is a timely challenge. In this contribution we apply the concept of isolobality to identify siloxides present at the surface of partially dehydroxylated silica as a suitable replacement for archetypal ligand architectures in organometallic SMMs. We demonstrate theoretically and experimentally that isolated siloxide anchorages not only enable successful immobilization, but also lead to two-orders-of-magnitude increase in magnetization relaxation times and provide magnetic site dilution.

scholarly journals Mn12 single molecule magnets deposited on μ-SQUID sensors: the role of interphases and structural modifications

Nanoscale ◽  
2013 ◽  
Vol 5 (24) ◽  
pp. 12565 ◽  
Author(s):  
Elena Bellido ◽  
Pablo González-Monje ◽  
Ana Repollés ◽  
Mark Jenkins ◽  
Javier Sesé ◽  
...  
Keyword(s):  
Single Molecule ◽  
Single Molecule Magnets ◽  
Structural Modifications
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