1
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Thermodynamics of General Heisenberg Spin Tetramers Composed of Coupled Quantum Dimers. MAGNETOCHEMISTRY 2021. [DOI: 10.3390/magnetochemistry7020029] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Advances in quantum computing technology have been made in recent years due to the evolution of spin clusters. Recent studies have tended towards spin cluster subgeometries to understand more complex structures better. These molecular magnets provide a multitude of phenomena via exchange interactions that allow for advancements in spintronics and other magnetic system applications due to the possibility of increasing speed, data storage, memory, and stability of quantum computing systems. Using the Heisenberg spin–spin exchange Hamiltonian and exact diagonalization, we examine the evolution of quantum energy levels and thermodynamic properties for various spin configurations and exchange interactions. The XXYY quantum spin tetramer considered in this study consists of two coupled dimers with exchange interactions α1J and α1′J and a dimer–dimer exchange interaction α2J. By varying spin values and interaction strengths, we determine the exact energy eigenstates that are used to determine closed-form analytic solutions for the heat capacity and magnetic susceptibility of the system and further analyze the evolution of the properties of the system based on the parameter values chosen. Furthermore, this study shows that the Schottky anomaly shifts towards zero as the ground-state of the system approaches a quantum phase transition between spin states. Additionally, we investigate the development of phase transitions produced by the convergence of the Schottky anomaly with both variable exchange interactions and external magnetic field.
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2
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Batool J, Hahn T, Pederson MR. Magnetic Signatures of Hydroxyl‐ and Water‐Terminated Neutral and Tetra‐Anionic Mn
12
‐Acetate. J Comput Chem 2019; 40:2301-2308. [DOI: 10.1002/jcc.26008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 03/23/2019] [Accepted: 06/09/2019] [Indexed: 12/20/2022]
Affiliation(s)
- Javaria Batool
- Department of Physics, Government College Women University, Madina Town Faisalbad Pakistan
| | - Torsten Hahn
- Institute for Theoretical Physics, Freiberg Technical University Freiberg Germany
| | - Mark R. Pederson
- Department of Chemistry Johns Hopkins University, TU Bergakademie Freiberg 21218 MD Baltimore
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3
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Thermodynamics and Magnetic Excitations in Quantum Spin Trimers: Applications for the Understanding of Molecular Magnets. CRYSTALS 2019. [DOI: 10.3390/cryst9020093] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Molecular magnets provide a playground of interesting phenomena and interactions that have direct applications for quantum computation and magnetic systems. A general understanding of the underlying geometries for molecular magnets therefore generates a consistent foundation for which further analysis and understanding can be established. Using a Heisenberg spin-spin exchange Hamiltonian, we investigate the evolution of magnetic excitations and thermodynamics of quantum spin isosceles trimers (two sides J and one side α J ) with increasing spin. For the thermodynamics, we produce exact general solutions for the energy eigenstates and spin decomposition, which can be used to determine the heat capacity and magnetic susceptibility quickly. We show how the thermodynamic properties change with α coupling parameters and how the underlying ground state governs the Schottky anomaly. Furthermore, we investigate the microscopic excitations by examining the inelastic neutron scattering excitations and structure factors. Here, we illustrate how the individual dimer subgeometry governs the ability for probing underlying excitations. Overall, we feel these calculations can help with the general analysis and characterization of molecular magnet systems.
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4
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Garlatti E, Chiesa A, Guidi T, Amoretti G, Santini P, Carretta S. Unravelling the Spin Dynamics of Molecular Nanomagnets with Four‐Dimensional Inelastic Neutron Scattering. Eur J Inorg Chem 2019. [DOI: 10.1002/ejic.201801050] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Elena Garlatti
- Dipartimento di Science Matematiche, Fisiche e Informatiche Università di Parma Parco Area delle Scienze n.7/A 43124 Parma Italy
- ISIS Neutron and Muon Source Rutherford Appleton Laboratory OX11 0QX Didcot UK
| | - Alessandro Chiesa
- Dipartimento di Science Matematiche, Fisiche e Informatiche Università di Parma Parco Area delle Scienze n.7/A 43124 Parma Italy
| | - Tatiana Guidi
- ISIS Neutron and Muon Source Rutherford Appleton Laboratory OX11 0QX Didcot UK
| | - Giuseppe Amoretti
- Dipartimento di Science Matematiche, Fisiche e Informatiche Università di Parma Parco Area delle Scienze n.7/A 43124 Parma Italy
| | - Paolo Santini
- Dipartimento di Science Matematiche, Fisiche e Informatiche Università di Parma Parco Area delle Scienze n.7/A 43124 Parma Italy
| | - Stefano Carretta
- Dipartimento di Science Matematiche, Fisiche e Informatiche Università di Parma Parco Area delle Scienze n.7/A 43124 Parma Italy
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5
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Planar polycubane single-molecule magnet [Ni6(pymeid)6Ni12(OH)6(µ3OH)16Cl2 (H2O)2]·38H2O: Experiment and theory. Inorganica Chim Acta 2018. [DOI: 10.1016/j.ica.2018.08.035] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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6
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7
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Perfetti M. Cantilever torque magnetometry on coordination compounds: from theory to experiments. Coord Chem Rev 2017. [DOI: 10.1016/j.ccr.2017.08.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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8
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Sottini S, Poneti G, Ciattini S, Levesanos N, Ferentinos E, Krzystek J, Sorace L, Kyritsis P. Magnetic Anisotropy of Tetrahedral Co II Single-Ion Magnets: Solid-State Effects. Inorg Chem 2016; 55:9537-9548. [PMID: 27636564 DOI: 10.1021/acs.inorgchem.6b00508] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This study reports the static and dynamic magnetic characterization of two mononuclear tetrahedral CoII complexes, [Co{iPr2P(E)NP(E)iPr2}2], where E = S (CoS4) and Se (CoSe4), which behave as single-ion magnets (SIMs). Low-temperature (15 K) single-crystal X-ray diffraction studies point out that the two complexes exhibit similar structural features in their first coordination sphere, but a disordered peripheral iPr group is observed only in CoS4. Although the latter complex crystallizes in an axial space group, the observed structural disorder leads to larger transverse magnetic anisotropy for the majority of the molecules compared to CoSe4, as confirmed by electron paramagnetic resonance spectroscopy. Static magnetic characterization indicates that both CoS4 and CoSe4 show easy-axis anisotropy, with comparable D values (∼-30 cm-1). Moreover, alternating-current susceptibility measurements on these CoII complexes, magnetically diluted in their isostructural ZnII analogues, highlight the role of dipolar magnetic coupling in the mechanism of magnetization reversal. In addition, our findings suggest that, despite their similar anisotropic features, CoS4 and CoSe4 relax magnetically via different processes. This work provides experimental evidence that solid-state effects may affect the magnetic behavior of SIMs.
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Affiliation(s)
- Silvia Sottini
- Department of Chemistry "Ugo Schiff" and INSTM Research Unit of Florence, University of Florence , via della Lastruccia 3-13, 50019 Sesto Fiorentino, Italy
| | - Giordano Poneti
- Department of Chemistry "Ugo Schiff" and INSTM Research Unit of Florence, University of Florence , via della Lastruccia 3-13, 50019 Sesto Fiorentino, Italy
| | - Samuele Ciattini
- Centro Interdipartimentale di Crystallografia Strutturale CRIST, University of Florence , via della Lastruccia 5, 50019 Sesto Fiorentino, Italy
| | - Nikolaos Levesanos
- Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens , Panepistimiopolis, GR-15771 Athens, Greece
| | - Eleftherios Ferentinos
- Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens , Panepistimiopolis, GR-15771 Athens, Greece
| | - J Krzystek
- National High Magnetic Field Laboratory (NHMFL), Florida State University , Tallahassee, Florida 32310, United States
| | - Lorenzo Sorace
- Department of Chemistry "Ugo Schiff" and INSTM Research Unit of Florence, University of Florence , via della Lastruccia 3-13, 50019 Sesto Fiorentino, Italy
| | - Panayotis Kyritsis
- Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens , Panepistimiopolis, GR-15771 Athens, Greece
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9
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Ghassemi Tabrizi S, Arbuznikov AV, Kaupp M. Understanding Thermodynamic and Spectroscopic Properties of Tetragonal Mn12 Single-Molecule Magnets from Combined Density Functional Theory/Spin-Hamiltonian Calculations. J Phys Chem A 2016; 120:6864-79. [PMID: 27482933 DOI: 10.1021/acs.jpca.6b06896] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Shadan Ghassemi Tabrizi
- Institut
für Chemie, Theoretische Chemie, Technische Universität Berlin, Sekr. C7, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Alexei V. Arbuznikov
- Institut
für Chemie, Theoretische Chemie, Technische Universität Berlin, Sekr. C7, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Martin Kaupp
- Institut
für Chemie, Theoretische Chemie, Technische Universität Berlin, Sekr. C7, Strasse des 17. Juni 135, 10623 Berlin, Germany
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10
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Glaser T, Hoeke V, Gieb K, Schnack J, Schröder C, Müller P. Quantum tunneling of the magnetization in [MnIII6M]3+ (M=CrIII, MnIII) SMMs: Impact of molecular and crystal symmetry. Coord Chem Rev 2015. [DOI: 10.1016/j.ccr.2014.12.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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11
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Deb A, Boron TT, Itou M, Sakurai Y, Mallah T, Pecoraro VL, Penner-Hahn JE. Understanding Spin Structure in Metallacrown Single-Molecule Magnets using Magnetic Compton Scattering. J Am Chem Soc 2014; 136:4889-92. [DOI: 10.1021/ja501452w] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Aniruddha Deb
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Thaddeus T. Boron
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Masayoshi Itou
- Japan Synchrotron
Radiation Research Institute (JASRI)/SPring-8, Sayo, Hyogo 679-5198, Japan
| | - Yoshiharu Sakurai
- Japan Synchrotron
Radiation Research Institute (JASRI)/SPring-8, Sayo, Hyogo 679-5198, Japan
| | - Talal Mallah
- Institut
de Chimie Moléculaire et des Matériaux d’Orsay,
CNRS, Université de Paris Sud, 91405 Orsay Cedex, France
| | - Vincent L. Pecoraro
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - James E. Penner-Hahn
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
- Program
in Biophysics, University of Michigan, Ann Arbor, Michigan 48109, United States
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12
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Zhu YY, Yin TT, Jiang SD, Barra AL, Wernsdorfer W, Neugebauer P, Marx R, Dörfel M, Wang BW, Wu ZQ, Slageren JV, Gao S. The solvent effect in an axially symmetric FeIII4 single-molecule magnet. Chem Commun (Camb) 2014; 50:15090-3. [DOI: 10.1039/c4cc07580c] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The axial symmetry of an FeIII4 SMM is broken by the interaction of the molecule with the disordered solvent molecules.
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Affiliation(s)
- Yuan-Yuan Zhu
- Key Laboratory of Advanced Functional Materials and Devices
- Anhui Province, School of Chemical Engineering
- Hefei University of Technology
- Hefei, P. R. China
- Beijing National Laboratory of Molecular Science
| | - Ting-Ting Yin
- Key Laboratory of Advanced Functional Materials and Devices
- Anhui Province, School of Chemical Engineering
- Hefei University of Technology
- Hefei, P. R. China
| | - Shang-Da Jiang
- 1. Physikalisches Institut
- Universität Stuttgart
- 70569 Stuttgart, Germany
- LNCMI-CNRS
- 38042 Grenoble Cedex 9, France
| | | | | | - Petr Neugebauer
- Institut für Physikalische Chemie
- Universität Stuttgart
- 70569 Stuttgart, Germany
| | - Raphael Marx
- Institut für Physikalische Chemie
- Universität Stuttgart
- 70569 Stuttgart, Germany
| | - María Dörfel
- Institut für Physikalische Chemie
- Universität Stuttgart
- 70569 Stuttgart, Germany
| | - Bing-Wu Wang
- Beijing National Laboratory of Molecular Science
- College of Chemistry and Molecular Engineering
- State Key Laboratory of Rare Earth Materials Chemistry and Applications
- Peking University
- Beijing, P. R. China
| | - Zong-Quan Wu
- Key Laboratory of Advanced Functional Materials and Devices
- Anhui Province, School of Chemical Engineering
- Hefei University of Technology
- Hefei, P. R. China
| | - Joris van Slageren
- Institut für Physikalische Chemie
- Universität Stuttgart
- 70569 Stuttgart, Germany
| | - Song Gao
- Beijing National Laboratory of Molecular Science
- College of Chemistry and Molecular Engineering
- State Key Laboratory of Rare Earth Materials Chemistry and Applications
- Peking University
- Beijing, P. R. China
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13
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Cervetti C, Heintze E, Bogani L. Interweaving spins with their environment: novel inorganic nanohybrids with controllable magnetic properties. Dalton Trans 2014; 43:4220-32. [PMID: 24514949 DOI: 10.1039/c3dt52650j] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We discuss the developments in the synthesis and characterization of magnetic nanohybrids made of molecular magnets and nanostructured materials.
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Affiliation(s)
| | - Eric Heintze
- Physikalisches Institut
- Universität Stuttgart
- Stuttgart, Germany
| | - Lapo Bogani
- Physikalisches Institut
- Universität Stuttgart
- Stuttgart, Germany
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14
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Hoeke V, Stammler A, Bögge H, Schnack J, Glaser T. Strong and Anisotropic Superexchange in the Single-Molecule Magnet (SMM) [MnIII6OsIII]3+: Promoting SMM Behavior through 3d–5d Transition Metal Substitution. Inorg Chem 2013; 53:257-68. [DOI: 10.1021/ic4022068] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Veronika Hoeke
- Lehrstuhl für Anorganische Chemie
I, Fakultät für Chemie, Universität Bielefeld, Universitätsstraße
25, D-33615 Bielefeld, Germany
| | - Anja Stammler
- Lehrstuhl für Anorganische Chemie
I, Fakultät für Chemie, Universität Bielefeld, Universitätsstraße
25, D-33615 Bielefeld, Germany
| | - Hartmut Bögge
- Lehrstuhl für Anorganische Chemie
I, Fakultät für Chemie, Universität Bielefeld, Universitätsstraße
25, D-33615 Bielefeld, Germany
| | - Jürgen Schnack
- Fakultät für Physik, Universität Bielefeld, Universitätsstraße 25, D-33615 Bielefeld, Germany
| | - Thorsten Glaser
- Lehrstuhl für Anorganische Chemie
I, Fakultät für Chemie, Universität Bielefeld, Universitätsstraße
25, D-33615 Bielefeld, Germany
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15
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16
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Adams ST, da Silva Neto EH, Datta S, Ware JF, Lampropoulos C, Christou G, Myaesoedov Y, Zeldov E, Friedman JR. Geometric-phase interference in a Mn12 single-molecule magnet with fourfold rotational symmetry. PHYSICAL REVIEW LETTERS 2013; 110:087205. [PMID: 23473196 DOI: 10.1103/physrevlett.110.087205] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Revised: 01/11/2013] [Indexed: 06/01/2023]
Abstract
We study the magnetic relaxation rate Γ of the single-molecule magnet Mn(12)-tBuAc as a function of the magnetic field component H(T) transverse to the molecule's easy axis. When the spin is near a magnetic quantum tunneling resonance, we find that Γ increases abruptly at certain values of H(T). These increases are observed just beyond values of H(T) at which a geometric-phase interference effect suppresses tunneling between two excited energy levels. The effect is washed out by rotating H(T) away from the spin's hard axis, thereby suppressing the interference effect. Detailed numerical calculations of Γ using the known spin Hamiltonian accurately reproduce the observed behavior. These results are the first experimental evidence for geometric-phase interference in a single-molecule magnet with true fourfold symmetry.
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Affiliation(s)
- S T Adams
- Department of Physics, Amherst College, Amherst, Massachusetts 01002-5000, USA
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17
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Farrell AR, Coome JA, Probert MR, Goeta AE, Howard JAK, Lemée-Cailleau MH, Parsons S, Murrie M. Ultra-low temperature structure determination of a Mn12 single-molecule magnet and the interplay between lattice solvent and structural disorder. CrystEngComm 2013. [DOI: 10.1039/c3ce00042g] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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18
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Lampropoulos C, Murugesu M, Harter AG, Wernsdofer W, Hill S, Dalal NS, Reyes AP, Kuhns PL, Abboud KA, Christou G. Synthesis, Structure, and Spectroscopic and Magnetic Characterization of [Mn12O12(O2CCH2But)16(MeOH)4]·MeOH, a Mn12 Single-Molecule Magnet with True Axial Symmetry. Inorg Chem 2012; 52:258-72. [DOI: 10.1021/ic301764t] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Christos Lampropoulos
- Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Muralee Murugesu
- Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Andrew G. Harter
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32310,
United States
| | - Wolfgang Wernsdofer
- Institut Néel, CNRS/UJF, BP 166, 25 Avenue des Martyrs,
38042, Grenoble, Cedex 9, France
| | - Stephen Hill
- Department
of Physics and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310,
United States
| | - Naresh S. Dalal
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32310,
United States
| | - Arneil P. Reyes
- Department
of Physics and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310,
United States
| | - Philip L. Kuhns
- Department
of Physics and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310,
United States
| | - Khalil A. Abboud
- Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - George Christou
- Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
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19
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Hoeke V, Heidemeier M, Krickemeyer E, Stammler A, Bögge H, Schnack J, Postnikov A, Glaser T. Environmental Influence on the Single-Molecule Magnet Behavior of [MnIII6CrIII]3+: Molecular Symmetry versus Solid-State Effects. Inorg Chem 2012; 51:10929-54. [DOI: 10.1021/ic301406j] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Veronika Hoeke
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, D-33615 Bielefeld, Germany
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20
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Kushch LA, Sasnovskaya VD, Dmitriev AI, Yagubskii EB, Koplak OV, Zorina LV, Boukhvalov DW. New single-molecule magnet based on Mn12 oxocarboxylate clusters with mixed carboxylate ligands, [Mn12O12(CN-o-C6H4CO2)12(CH3CO2)4(H2O)4]·8CH2Cl2: Synthesis, crystal and electronic structure, magnetic properties. Dalton Trans 2012; 41:13747-54. [DOI: 10.1039/c2dt31173a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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21
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Hoeke V, Heidemeier M, Krickemeyer E, Stammler A, Bögge H, Schnack J, Glaser T. Structural influences on the exchange coupling and zero-field splitting in the single-molecule magnet [MnIII6MnIII]3+. Dalton Trans 2012; 41:12942-59. [DOI: 10.1039/c2dt31590d] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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22
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Burzurí E, Luis F, Barbara B, Ballou R, Ressouche E, Montero O, Campo J, Maegawa S. Magnetic dipolar ordering and quantum phase transition in an Fe8 molecular magnet. PHYSICAL REVIEW LETTERS 2011; 107:097203. [PMID: 21929265 DOI: 10.1103/physrevlett.107.097203] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Indexed: 05/31/2023]
Abstract
We show that a crystal of mesoscopic Fe(8) single-molecule magnets is an experimental realization of the quantum Ising model in a transverse field, with dipolar interactions. Quantum annealing has enabled us to explore the quantum and classical phase transitions between the paramagnetic and ferromagnetic phases, at thermodynamical equilibrium. The phase diagram and critical exponents that we obtain agree with expectations for the mean-field universality class.
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Affiliation(s)
- E Burzurí
- Instituto de Ciencia de Materiales de Aragón, C.S.I.C.-Universidad de Zaragoza, and Departamento de Física de la Materia Condensada, Universidad de Zaragoza, E-50009 Zaragoza, Spain
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23
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Nippe M, Wang J, Bill E, Hope H, Dalal NS, Berry JF. Crystals in which some metal atoms are more equal than others: inequalities from crystal packing and their spectroscopic/magnetic consequences. J Am Chem Soc 2011; 132:14261-72. [PMID: 20860382 DOI: 10.1021/ja106510g] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Crystal structures of the heterometallic compounds CrCrFe(dpa)(4)Cl(2) (1), CrCrMn(dpa)(4)Cl(2) (2), and MoMoMn(dpa)(4)Cl(2) (3) (dpa = 2,2'-dipyridylamide) show disorder in the metal atom positions such that the linear M(A)[quadruple bond]M(A)···M(B) array for a given molecule in the crystal is oriented in one of two opposing directions. Despite the fact that the direct coordination sphere of the metals in the two crystallographically independent orientations is identical, subtle differences in some metal-ligand bond distances are observed in 1 and 3 due to differences in the orientation of a solvent molecule of crystallization. The Fe(II) and Mn(II) ions serve as sensitive local spectroscopic probes that have been interrogated by Mössbauer spectroscopy and high-field EPR spectroscopy, respectively. The subtle differences in the two independent Fe and Mn sites in 1 and 3 unexpectedly give rise to unusually large differences in the measured Fe quadrupole splitting (ΔE(Q)) in 1 and Mn zero-field splitting (D) in 3. Variable-temperature/single-crystal EPR spectroscopy has allowed us to determine that the temperature-dependent D tensors in 3 are oriented along the metal-metal axis and that they show significantly different dynamic behavior with temperature. The differences in ΔE(Q) and D are reproduced by density functional calculations on truncated models for 1 and 3 that lack the quadruply bonded M(A)[quadruple bond]M(A) groups, though the magnitude of the calculated effect is not as large as that observed experimentally. We suggest that the large observed differences in ΔE(Q) and D for the individual sites could be due to the influence of the strong diamagnetic anisotropy of the quadruply bonded M[quadruple bond]M unit.
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Affiliation(s)
- Michael Nippe
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA
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24
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Glaser T. Rational design of single-molecule magnets: a supramolecular approach. Chem Commun (Camb) 2011; 47:116-30. [DOI: 10.1039/c0cc02259d] [Citation(s) in RCA: 190] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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25
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Boukhvalov DW, Dobrovitski VV, Kögerler P, Al-Saqer M, Katsnelson MI, Lichtenstein AI, Harmon BN. Effect of Ligand Substitution on the Exchange Interactions in {Mn12}-Type Single-Molecule Magnets. Inorg Chem 2010; 49:10902-6. [DOI: 10.1021/ic101229p] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Danil W. Boukhvalov
- Computational Materials Science Center, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
- Radboud University Nijmegen, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | | | - Paul Kögerler
- Ames Laboratory, Iowa State University, Ames, Iowa 50011, United States
- Institute of Inorganic Chemistry, RWTH Aachen University, 52074 Aachen, Germany
| | - Mohammad Al-Saqer
- Ames Laboratory, Iowa State University, Ames, Iowa 50011, United States
| | - Mikhail I. Katsnelson
- Radboud University Nijmegen, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | | | - Bruce N. Harmon
- Ames Laboratory, Iowa State University, Ames, Iowa 50011, United States
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Dreiser J, Waldmann O, Carver G, Dobe C, Güdel HU, Weihe H, Barra AL. High-Frequency Electron-Spin-Resonance Study of the Octanuclear Ferric Wheel CsFe8. Inorg Chem 2010; 49:8729-35. [DOI: 10.1021/ic100664g] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jan Dreiser
- Physikalisches Institut, Universität Freiburg, D-79104 Freiburg, Germany
| | - Oliver Waldmann
- Physikalisches Institut, Universität Freiburg, D-79104 Freiburg, Germany
| | - Graham Carver
- Department of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland
| | - Christopher Dobe
- Department of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland
| | - Hans-Ulrich Güdel
- Department of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland
| | - Høgni Weihe
- Department of Chemistry, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Anne-Laure Barra
- Grenoble High Magnetic Field Laboratory, CNRS, BP 166, 38042 Grenoble Cedex 9, France
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Gonidec M, Luis F, Vílchez À, Esquena J, Amabilino D, Veciana J. A Liquid-Crystalline Single-Molecule Magnet with Variable Magnetic Properties. Angew Chem Int Ed Engl 2010; 49:1623-6. [DOI: 10.1002/anie.200905007] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Gonidec M, Luis F, Vílchez À, Esquena J, Amabilino D, Veciana J. A Liquid-Crystalline Single-Molecule Magnet with Variable Magnetic Properties. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.200905007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Ramasesha S, Sahoo S, Raghunathan R, Sen D. Computing magnetic anisotropy constants of single molecule magnets. J CHEM SCI 2009. [DOI: 10.1007/s12039-009-0098-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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van Wüllen C. Magnetic anisotropy from density functional calculations. Comparison of different approaches: Mn12O12 acetate as a test case. J Chem Phys 2009; 130:194109. [PMID: 19466823 DOI: 10.1063/1.3134430] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Magnetic anisotropy is the capability of a system in a triplet or higher spin state to store magnetic information. Although the source of the magnetic anisotropy is the zero-field splitting of the ground state of the system, there is a difference between these two quantities that has to be fully rationalized before one makes comparisons. This is especially important for small spins such as triplets, where the magnetic anisotropy energy is only half of the zero-field splitting. Density functional calculations of magnetic anisotropy energies correspond to a high-field limit where the spins are aligned by the external magnetic field. Data are presented for the well-studied molecular magnet Mn(12)O(12) acetate. Both perturbative and self-consistent treatments, different quasirelativistic Hamiltonians (zeroth order regular approximation, Douglas-Kroll, effective core potentials) and exchange-correlation functionals are compared. It is shown that some effects usually considered minor, such as the inclusion of the exchange-correlation potential in the effective one-particle spin-orbit operator, lead to sizable differences when computing magnetic anisotropy energies. Higher-order contributions, that is, the difference between self-consistent and perturbative results, increase the magnetic anisotropy energy somewhat but do not introduce sizeable quartic terms or an in-plane anisotropy. In numerical experiments, on can switch off and on spin-orbit coupling at individual atomic sites. This procedure yields single-site contributions to the overall magnetic anisotropy energy that could be used as parameters in phenomenological spin Hamiltonians. If ferrimagnetic systems are treated with broken symmetry density functional methods where the Kohn-Sham reference function is not a spin eigenfunction, corrections are needed which depend on the size of the exchange couplings in the system and must therefore be evaluated case by case.
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Affiliation(s)
- Christoph van Wüllen
- Fachbereich Chemie, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany.
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Henderson JJ, Koo C, Feng PL, del Barco E, Hill S, Tupitsyn IS, Stamp PCE, Hendrickson DN. Manifestation of spin selection rules on the quantum tunneling of magnetization in a single-molecule magnet. PHYSICAL REVIEW LETTERS 2009; 103:017202. [PMID: 19659173 DOI: 10.1103/physrevlett.103.017202] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2009] [Revised: 05/06/2009] [Indexed: 05/28/2023]
Abstract
We present low temperature magnetometry measurements on a new Mn3 single-molecule magnet in which the quantum tunneling of magnetization (QTM) displays clear evidence for quantum mechanical selection rules. A QTM resonance appearing only at high temperatures demonstrates tunneling between excited states with spin projections differing by a multiple of three. This is dictated by the C3 molecular symmetry, which forbids pure tunneling from the lowest metastable state. Transverse field resonances are understood by correctly orienting the Jahn-Teller axes of the individual manganese ions and including transverse dipolar fields. These factors are likely to be important for QTM in all single-molecule magnets.
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Affiliation(s)
- J J Henderson
- Department of Physics, University of Central Florida, Orlando, Florida 32816, USA
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Gregoli L, Danieli C, Barra AL, Neugebauer P, Pellegrino G, Poneti G, Sessoli R, Cornia A. Magnetostructural Correlations in Tetrairon(III) Single-Molecule Magnets. Chemistry 2009; 15:6456-67. [DOI: 10.1002/chem.200900483] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Bagai R, Christou G. The Drosophila of single-molecule magnetism: [Mn12O12(O2CR)16(H2O)4]. Chem Soc Rev 2009; 38:1011-26. [PMID: 19421579 DOI: 10.1039/b811963e] [Citation(s) in RCA: 520] [Impact Index Per Article: 34.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Single-molecule magnets (SMMs) are individual molecules that can function as nanoscale magnetic particles. The [Mn12O12(O2CR)16(H2O)4] (Mn12; R=Me, Et, etc.) family of SMMs was the first one discovered; it is also the one whose study has provided the majority of current knowledge on this interesting magnetic phenomenon, prompting its description here as the Drosophila of the field. This tutorial review will survey the various chemical studies that have been carried out to date on this family. This will include a discussion of methods that have been developed for their structural and redox transformation, and the effect of the latter on the magnetic and SMM properties.
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Affiliation(s)
- Rashmi Bagai
- Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, USA
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Lawrence J, Yang EC, Hendrickson DN, Hill S. Magnetic quantum tunneling: key insights from multi-dimensional high-field EPR. Phys Chem Chem Phys 2009; 11:6743-9. [DOI: 10.1039/b908460f] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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35
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Classical and quantum nonlinear phenomena in molecular magnetic clusters. CR CHIM 2008. [DOI: 10.1016/j.crci.2008.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Carbonera C, Imaz I, Maspoch D, Ruiz-Molina D, Luis F. Magnetic behaviour of Mn12 single-molecule magnet nanospheres. Inorganica Chim Acta 2008. [DOI: 10.1016/j.ica.2008.03.037] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Barra A. High- and multi-frequency EPR study of Mn12: A new technique for studying new objects. Inorganica Chim Acta 2008. [DOI: 10.1016/j.ica.2008.03.057] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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38
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Molecular magnets based on two-dimensional Mn(II)–nitronyl nitroxide frameworks in layered structures. Inorganica Chim Acta 2008. [DOI: 10.1016/j.ica.2008.03.109] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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39
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Origin of magnetization tunneling in single-molecule magnets as determined by single-crystal high-frequency EPR. Inorganica Chim Acta 2008. [DOI: 10.1016/j.ica.2008.02.074] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Lawrence J, Yang EC, Edwards R, Olmstead MM, Ramsey C, Dalal NS, Gantzel PK, Hill S, Hendrickson DN. Disorder and Intermolecular Interactions in a Family of Tetranuclear Ni(II) Complexes Probed by High-Frequency Electron Paramagnetic Resonance. Inorg Chem 2008; 47:1965-74. [DOI: 10.1021/ic701416w] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jon Lawrence
- Department of Physics, University of Florida, Gainesville, Florida 32611-8440, Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California 92093-0358, Department of Chemistry and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, and Department of Chemistry, University of California at Davis, Davis, California 95616
| | - En-Che Yang
- Department of Physics, University of Florida, Gainesville, Florida 32611-8440, Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California 92093-0358, Department of Chemistry and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, and Department of Chemistry, University of California at Davis, Davis, California 95616
| | - Rachel Edwards
- Department of Physics, University of Florida, Gainesville, Florida 32611-8440, Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California 92093-0358, Department of Chemistry and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, and Department of Chemistry, University of California at Davis, Davis, California 95616
| | - Marilyn M. Olmstead
- Department of Physics, University of Florida, Gainesville, Florida 32611-8440, Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California 92093-0358, Department of Chemistry and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, and Department of Chemistry, University of California at Davis, Davis, California 95616
| | - Chris Ramsey
- Department of Physics, University of Florida, Gainesville, Florida 32611-8440, Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California 92093-0358, Department of Chemistry and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, and Department of Chemistry, University of California at Davis, Davis, California 95616
| | - Naresh S. Dalal
- Department of Physics, University of Florida, Gainesville, Florida 32611-8440, Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California 92093-0358, Department of Chemistry and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, and Department of Chemistry, University of California at Davis, Davis, California 95616
| | - Peter K. Gantzel
- Department of Physics, University of Florida, Gainesville, Florida 32611-8440, Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California 92093-0358, Department of Chemistry and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, and Department of Chemistry, University of California at Davis, Davis, California 95616
| | - Stephen Hill
- Department of Physics, University of Florida, Gainesville, Florida 32611-8440, Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California 92093-0358, Department of Chemistry and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, and Department of Chemistry, University of California at Davis, Davis, California 95616
| | - David N. Hendrickson
- Department of Physics, University of Florida, Gainesville, Florida 32611-8440, Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California 92093-0358, Department of Chemistry and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, and Department of Chemistry, University of California at Davis, Davis, California 95616
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Imaz I, Luis F, Carbonera C, Ruiz-Molina D, Maspoch D. Single-molecule magnet behaviour in metal–organic nanospheres generated by simple precipitation of Mn12O12 clusters. Chem Commun (Camb) 2008:1202-4. [DOI: 10.1039/b716071b] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Harter A, Lampropoulos C, Murugesu M, Kuhns P, Reyes A, Christou G, Dalal N. 55Mn nuclear spin relaxation in the truly axial single-molecule magnet Mn12-t-butylacetate thermally-activated down to 400mK. Polyhedron 2007. [DOI: 10.1016/j.poly.2006.11.039] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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43
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Milios CJ, Inglis R, Bagai R, Wernsdorfer W, Collins A, Moggach S, Parsons S, Perlepes SP, Christou G, Brechin EK. Enhancing SMM properties in a family of [Mn6] clusters. Chem Commun (Camb) 2007:3476-8. [PMID: 17700887 DOI: 10.1039/b705170k] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The complex [Mn(6)O(2)(Et-sao)(6)(O(2)C(11)H(15))(2)(EtOH)(6)] has U(eff) = 80 K.
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Synthesis, crystal structure and magnetism of a single-molecule magnet, [Mn16O16(OMe)6(OAc)16(MeOH)3(H2O)3]·6H2O, and of a mixed bridge 1D chain, [Mn(μ-OMe)(μ-OAc)2]n. Polyhedron 2007. [DOI: 10.1016/j.poly.2006.05.044] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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45
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Yang EC, Wernsdorfer W, Zakharov LN, Karaki Y, Yamaguchi A, Isidro RM, Lu GD, Wilson SA, Rheingold AL, Ishimoto H, Hendrickson DN. Fast magnetization tunneling in tetranickel(II) single-molecule magnets. Inorg Chem 2006; 45:529-46. [PMID: 16411688 DOI: 10.1021/ic050093r] [Citation(s) in RCA: 172] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of Ni(4) cubane complexes with the composition [Ni(hmp)(ROH)Cl](4) complexes 1-4 where R= -CH(3) (complex 1), -CH(2)CH(3) (complex 2), -CH(2)CH(2)(C(4)H(9)) (complex 3), -CH(2)CH(2)CH(2)(C(6)H(11)) (complex 4), hmp(-) is the anion of 2-hydroxymethylpyridine, t-Buhmp(-) is the anion of 4-tert-butyl-2-hydroxymethylpyridine, and dmb is 3,3-dimethyl-1-butanol] and [Ni(hmp)(dmb)Br](4) (complex 5) and [Ni(t-Buhmp)(dmb)Cl](4) (complex 6) were prepared. All six complexes were characterized by dc magnetic susceptibility data to be ferromagnetically coupled to give an S = 4 ground state with significant magnetoanisotropy (D approximately equal to -0.6 cm(-1)). Magnetization hysteresis measurements carried out on single crystals of complexes 1-6 establish the single-molecule magnet (SMM) behavior of these complexes. The exchange bias observed in the magnetization hysteresis loops of complexes 1 and 2 is dramatically decreased to zero in complex 3, where the bulky dmb ligand is employed. Fast tunneling of magnetization is observed for the high-symmetry (S(4) site symmetry) Ni(4) complexes in the crystal of complex 3, and the tunneling rate can even be enhanced by destroying the S(4) site symmetry, as is the case for complex 4, where there are two crystallographically different Ni(4) molecules, one with C(2) and the other with C(1) site symmetry. Magnetic ordering temperatures due to intermolecular dipolar and magnetic exchange interactions were determined by means of very low-temperature ac susceptibility measurements; complex 1 orders at 1100 mK, complex 3 at 290 mK, complex 4 at approximately 80 mK, and complex 6 at <50 mK. This confirms that bulkier ligands correspond to more isolated molecules, and therefore, magnetic ordering occurs at lower temperatures for those complexes with the bulkiest ligands.
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Affiliation(s)
- En-Che Yang
- Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, CA 92093-0358, USA
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Carver G, Dobe C, Jensen TB, Tregenna-Piggott PLW, Janssen S, Bill E, McIntyre GJ, Barra AL. Spectroscopic, Magnetochemical, and Crystallographic Study of Cesium Iron Phosphate Hexahydrate: Characterization of the Electronic Structure of the Iron(II) Hexa-aqua Cation in a Quasicubic Environment. Inorg Chem 2006; 45:4695-705. [PMID: 16749833 DOI: 10.1021/ic0601889] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Spectroscopic, magnetochemical, and crystallographic data are presented for CsFe(H2O)6PO4, a member of a little-known isomorphous series of salts that facilitates the study of hexa-aqua ions in a quasicubic environment. Above 120 K, the deviations from cubic symmetry are minimal, as shown by the first example of an iron(II) Mössbauer spectrum that exhibits no measurable quadrupole splitting. Two crystallographically distinct [Fe(OH2)6]2+ complexes are identified from inelastic neutron-scattering (INS) experiments conducted between 2 and 15 K. The data are modeled with the ligand-field Hamiltonian, H = lambdaLŝ + betaB(kL + 2ŝ) + Delta(tet){Lz2 - (1/3)L(L + 1)} + Delta(rhom){Lx2 - Ly2}, operating in the ground-term (5)T(2g) (Oh) basis. An excellent reproduction of INS, Mössbauer, HF-EPR, and magnetochemical data are obtained in the 2 and 15 K temperature regimes with the following parameters: lambda = -80 cm(-1); k = 0.8; site A Delta(tet) = 183 cm(-1), Delta(rhom)= 19 cm(-1); site B Delta(tet) = 181 cm(-1), Delta(rhom)= 12 cm(-1). The corresponding zero-field-splitting (ZFS) parameters of the conventional S = 2 spin Hamiltonian are as follows: site A D = 12.02 cm(-)(1), E = 2.123 cm(-1); site B D = 12.15 cm(-1), E = 1.37 cm(-1). A theoretical analysis of the variation of the energies of the low-lying states with respect to displacements along selected normal coordinates of the [Fe(OH2)6]2+, shows the zero-field splitting to be extremely sensitive to small structural perturbations of the complex. The expressions derived are discussed in the context of spin-Hamiltonian parameters reported for the [Fe(OH2)6]2+ cation in different crystalline environments.
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Affiliation(s)
- Graham Carver
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
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Chakov NE, Lee SC, Harter AG, Kuhns PL, Reyes AP, Hill SO, Dalal NS, Wernsdorfer W, Abboud KA, Christou G. The Properties of the [Mn12O12(O2CR)16(H2O)4] Single-Molecule Magnets in Truly Axial Symmetry: [Mn12O12(O2CCH2Br)16(H2O)4]·4CH2Cl2. J Am Chem Soc 2006; 128:6975-89. [PMID: 16719478 DOI: 10.1021/ja060796n] [Citation(s) in RCA: 154] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Detailed studies are reported of a Mn(12) single-molecule magnet (SMM) in truly axial (tetragonal) symmetry. The complex is [Mn(12)O(12)(O(2)CCH(2)Br)(16)(H(2)O)(4)].4CH(2)Cl(2) (2.4CH(2)Cl(2) or Mn(12)-BrAc), obtained by the standard carboxylate substitution method. The complex has an S = 10 ground state, typical of the Mn(12) family, and displays frequency-dependent out-of-phase AC susceptibility signals and hysteresis in single-crystal magnetization vs applied DC field sweeps. Single-crystal high-frequency EPR spectra in frequencies up to 360 GHz exhibit narrow signals that are not overlapping multiplets, in contrast to [Mn(12)O(12)(O(2)CMe)(16)(H(2)O)(4)].2MeCO(2)H.4H(2)O (1 or Mn(12)-Ac), which also crystallizes in an axial (tetragonal) space group but which now is recognized to consist of a mixture of six hydrogen-bonded isomers in the crystal and thus gives multiple, inhomogeneously broadened EPR signals. Similarly, single-crystal (55)Mn NMR spectra on Mn(12)-BrAc display much sharper signals than a single crystal of Mn(12)-Ac, and this allows one Mn(III) signal to show an almost baseline-resolved quintet from quadrupolar splitting ((55)Mn, I = 5/2, 100%), allowing quadrupole coupling parameters (e(2)qQ) to be determined. In addition, it was found that crushing crystals of Mn(12)-BrAc into a microcrystalline powder causes severe broadening and shifts of the NMR resonances, emphasizing the superiority of single-crystal studies. The combined results establish that Mn(12)-BrAc is far superior to Mn(12)-Ac for the study of the intrinsic properties of the Mn(12) family of SMMs in axial symmetry, and for the search for new phenomena such as quantum interference effects caused by higher-order (>2nd-order) transverse terms in the spin Hamiltonian.
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Affiliation(s)
- Nicole E Chakov
- Department of Chemistry, University of Florida, Gainesville, FL 32611, USA
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