scholarly journals Determining Key Local Vibrations in the Relaxation of Molecular Spin Qubits and Single-Molecule Magnets

2017 ◽  
Vol 8 (7) ◽  
pp. 1695-1700 ◽  
Author(s):  
L. Escalera-Moreno ◽  
N. Suaud ◽  
A. Gaita-Ariño ◽  
E. Coronado
2012 ◽  
Vol 485 ◽  
pp. 522-525
Author(s):  
Hai Mei Xiao ◽  
Li Chun Shi

In the basic and applied research, the electronics and spin degrees of freedom is a very promising field of research and development over the past decade, spintronics from fundamental physics to technical devices already have a great deal of progress. This study made an overview of the synthesis, structure and properties of single molecular magnets and their applications in molecular spin combined with the latest research on this study sphere. Single molecular magnets are made of inner magnetic nuclei and peripheral organic molecule lamella, which can improve physical and chemical properties by means of adorn radical of organic ligand and exchange internal magnetic ions. And this paper also analyzes the molecular spin of the electron spin and charge electronic devices at the molecular level.


Author(s):  
Theocharis C Stamatatos ◽  
George Christou

Mixed-valent Mn/O dinuclear and polynuclear molecular compounds containing Mn III are almost without exception trapped valence. Large differences between the strengths of the exchange interactions within Mn II Mn III , Mn III Mn III and Mn III Mn IV pairs lead to situations where Mn III Mn IV interactions, the strongest of the three mentioned and antiferromagnetic in nature, dominate the intramolecular spin alignments in trinuclear and higher nuclearity mixed-valent complexes and often result in molecules that have large, and sometimes abnormally large, values of molecular spin ( S ). When coupled to a large molecular magnetoanisotropy of the easy-axis-type (negative zero-field splitting parameter, D ), also primarily resulting from individual Jahn–Teller distorted Mn III centres, such molecules will function as single-molecule magnets (molecular nanomagnets). Dissection of the structures and exchange interactions within a variety of mixed-valent Mn x cluster molecules with metal nuclearities of Mn 4 , Mn 12 and Mn 25 allows a ready rationalization of the observed S , D and overall magnetic properties in terms of competing antiferromagnetic exchange interactions within triangular subunits, resulting spin alignments and relative orientation of Mn III JT axes. Such an understanding has provided a stepping stone to the identification of a ‘magnetically soft’ Mn 25 cluster whose groundstate spin S value can be significantly altered by relatively minor structural perturbations. Such ‘spin tweaking’ has allowed this cluster to be obtained in three different forms with three different groundstate S values.


2018 ◽  
Vol 47 (16) ◽  
pp. 5533-5537 ◽  
Author(s):  
S. Cardona-Serra ◽  
A. Gaita-Ariño

The combination of a cutting-edge project of rational design of molecular spin qubits and a series of experiments in molecular spintronics for quantum computing are reviewed and discussed.


2010 ◽  
Vol 96 (8) ◽  
pp. 082115 ◽  
Author(s):  
L. Zhu ◽  
K. L. Yao ◽  
Z. L. Liu

2019 ◽  
Author(s):  
Guo-Zhang Huang ◽  
Ze-Yu Ruan ◽  
Jie-Yu Zheng ◽  
Yan-Cong Chen ◽  
Si-Guo Wu ◽  
...  

<p><a></a>Controlling molecular magnetic anisotropy via structural engineering is delicate and fascinating, especially for single-molecule magnets (SMMs). Herein a family of dysprosium single-ion magnets (SIMs) sitting in pentagonal bipyramid geometry have been synthesized with the variable-size terminal ligands and counter anions, through which the subtle coordination geometry of Dy(III) can be finely tuned based on the size effect. The effective energy barrier (Ueff) successfully increases from 439 K to 632 K and the magnetic hysteresis temperature (under a 200 Oe/s sweep rate) raises from 11 K to 24 K. Based on the crystal-field theory, a semi-quantitative magneto-structural correlation deducing experimentally for the first time is revealed that the Ueff is linearly proportional to the structural-related value S2<sup>0</sup> corresponding to the axial coordination bond lengths and the bond angles. Through the evaluation of the remanent magnetization from hysteresis, quantum tunneling of magnetization (QTM) is found to exhibit negative correlation with the structural-related value S<sub>tun</sub> corresponding to the axial coordination bond angles.<br></p>


2018 ◽  
Author(s):  
Marcus J. Giansiracusa ◽  
Andreas Kostopoulos ◽  
George F. S. Whitehead ◽  
David Collison ◽  
Floriana Tuna ◽  
...  

We report a six coordinate DyIII single-molecule magnet<br>(SMM) with an energy barrier of 1110 K for thermal relaxation of<br>magnetization. The sample shows no retention of magnetization<br>even at 2 K and this led us to find a good correlation between the<br>blocking temperature and the Raman relaxation regime for SMMs.<br>The key parameter is the relaxation time (𝜏<sub>switch</sub>) at the point where<br>the Raman relaxation mechanism becomes more important than<br>Orbach.


2018 ◽  
Author(s):  
Shannon Houck ◽  
Nicholas Mayhall

<div>Many multiconfigurational systems, such as single-molecule magnets, are difficult to study using traditional computational methods due to the simultaneous existence of both spin and spatial degeneracies. In this work, a new approach termed n-spin-flip Ionization Potential/Electron Affinity (<i>n</i>SF-IP or <i>n</i>SF-EA) is introduced which combines the spin-flip method of Anna Krylov with particle-number changing IP/EA methods. We demonstrate the efficacy of the approach by applying it to the strongly-correlated N<sub>2</sub><sup>+</sup> as well as several double exchange systems. We also demonstrate that when these systems are well-described by a double exchange model Hamiltonian, only 1SF-IP/EA is required to extract the double exchange parameters and accurately predict energies for the low-spin states. This significantly reduces the computational effort for studying such systems. The effects of including additional excitations (using a RAS-<i>n</i>SF-IP/EA scheme) are also examined, with particular emphasis on hole and particle excitations.</div>


2018 ◽  
Author(s):  
Shannon Houck ◽  
Nicholas Mayhall

<div>Many multiconfigurational systems, such as single-molecule magnets, are difficult to study using traditional computational methods due to the simultaneous existence of both spin and spatial degeneracies. In this work, a new approach termed n-spin-flip Ionization Potential/Electron Affinity (<i>n</i>SF-IP or <i>n</i>SF-EA) is introduced which combines the spin-flip method of Anna Krylov with particle-number changing IP/EA methods. We demonstrate the efficacy of the approach by applying it to the strongly-correlated N<sub>2</sub><sup>+</sup> as well as several double exchange systems. We also demonstrate that when these systems are well-described by a double exchange model Hamiltonian, only 1SF-IP/EA is required to extract the double exchange parameters and accurately predict energies for the low-spin states. This significantly reduces the computational effort for studying such systems. The effects of including additional excitations (using a RAS-<i>n</i>SF-IP/EA scheme) are also examined, with particular emphasis on hole and particle excitations.</div>


2013 ◽  
Vol 3 (2) ◽  
pp. 101-111 ◽  
Author(s):  
Peng Zhang ◽  
Li Zhang ◽  
Jinkui Tang

Author(s):  
Jean-Pierre Launay ◽  
Michel Verdaguer

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.


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