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Fix M, Atkinson JH, Canfield PC, Del Barco E, Jesche A. Extreme Field Sensitivity of Magnetic Tunneling in Fe-Doped Li_{3}N. PHYSICAL REVIEW LETTERS 2018; 120:147202. [PMID: 29694147 DOI: 10.1103/physrevlett.120.147202] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 01/29/2018] [Indexed: 06/08/2023]
Abstract
The magnetic properties of dilute Li_{2}(Li_{1-x}Fe_{x})N with x∼0.001 are dominated by the spin of single, isolated Fe atoms. Below T=10 K the spin-relaxation times become temperature independent indicating a crossover from thermal excitations to the quantum tunneling regime. We report on a strong increase of the spin-flip probability in transverse magnetic fields that proves the resonant character of this tunneling process. Longitudinal fields, on the other hand, lift the ground-state degeneracy and destroy the tunneling condition. An increase of the relaxation time by 4 orders of magnitude in applied fields of only a few milliTesla reveals exceptionally sharp tunneling resonances. Li_{2}(Li_{1-x}Fe_{x})N represents a comparatively simple and clean model system that opens the possibility to study quantum tunneling of the magnetization at liquid helium temperatures.
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Affiliation(s)
- M Fix
- EP VI, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, D-86159 Augsburg, Germany
| | - J H Atkinson
- Department of Physics, University of Central Florida, Orlando, Florida 32816, USA
| | - P C Canfield
- The Ames Laboratory, Iowa State University, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - E Del Barco
- Department of Physics, University of Central Florida, Orlando, Florida 32816, USA
| | - A Jesche
- EP VI, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, D-86159 Augsburg, Germany
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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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Atkinson JH, Inglis R, del Barco E, Brechin EK. Three-leaf quantum interference clovers in a trigonal single-molecule magnet. PHYSICAL REVIEW LETTERS 2014; 113:087201. [PMID: 25192120 DOI: 10.1103/physrevlett.113.087201] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Indexed: 06/03/2023]
Abstract
We report on a single-molecule magnet where the spatial arrangement of three manganese ions and their spin-orbit coupling tensor orientations result in threefold angular modulations of the magnetization tunneling rates and quantum interference patterns that mimic the form of a three-leaf clover. Although expected in all quantum tunneling of magnetization resonances for a trigonal molecular symmetry, the threefold modulation only appears at resonances for which a longitudinal magnetic field is applied (i.e., resonance numbers |k|>0). A sixfold transverse field modulation observed at resonance k = 0 manifests as a direct consequence of a threefold corrugation of the spin-orbit coupling energy landscape, creating an effective longitudinal field which varies the resonance condition in the presence of a transverse field. The observations allow for an association between the trigonal distortion of the local spin-orbit interactions and the spatial disposition of the constituent ions, a finding that can be extrapolated to other systems where spin-orbit coupling plays a significant role.
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Affiliation(s)
- James H Atkinson
- Department of Physics, University of Central Florida, Orlando, Florida 32765, USA
| | - Ross Inglis
- EaStCHEM School of Chemistry, The University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, United Kingdom
| | - Enrique del Barco
- Department of Physics, University of Central Florida, Orlando, Florida 32765, USA
| | - Euan K Brechin
- EaStCHEM School of Chemistry, The University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, United Kingdom
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Boulon ME, Cucinotta G, Liu SS, Jiang SD, Ungur L, Chibotaru LF, Gao S, Sessoli R. Angular-Resolved Magnetometry Beyond Triclinic Crystals: Out-of-Equilibrium Studies of Cp*ErCOT Single-Molecule Magnet. Chemistry 2013; 19:13726-31. [DOI: 10.1002/chem.201302600] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Indexed: 11/10/2022]
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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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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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Density Matrix Equation for a Bathed Small System and its Application to Molecular Magnets. ADVANCES IN CHEMICAL PHYSICS 2011. [DOI: 10.1002/9781118135242.ch4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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Quddusi HM, Liu J, Singh S, Heroux KJ, del Barco E, Hill S, Hendrickson DN. Asymmetric Berry-phase interference patterns in a single-molecule magnet. PHYSICAL REVIEW LETTERS 2011; 106:227201. [PMID: 21702626 DOI: 10.1103/physrevlett.106.227201] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Indexed: 05/31/2023]
Abstract
A Mn(4) single-molecule magnet displays asymmetric Berry-phase interference patterns in the transverse-field (H(T)) dependence of the magnetization tunneling probability when a longitudinal field (H(L)) is present, contrary to symmetric patterns observed for H(L)=0. Reversal of H(L) results in a reflection of the transverse-field asymmetry about H(T)=0, as expected on the basis of the time-reversal invariance of the spin-orbit Hamiltonian which is responsible for the tunneling oscillations. A fascinating motion of Berry-phase minima within the transverse-field magnitude-direction phase space results from a competition between noncollinear magnetoanisotropy tensors at the two distinct Mn sites.
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Affiliation(s)
- H M Quddusi
- Department of Physics, University of Central Florida, Orlando, Florida 32816, USA
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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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Hill S, Datta S, Liu J, Inglis R, Milios CJ, Feng PL, Henderson JJ, del Barco E, Brechin EK, Hendrickson DN. Magnetic quantum tunneling: insights from simple molecule-based magnets. Dalton Trans 2010; 39:4693-707. [DOI: 10.1039/c002750b] [Citation(s) in RCA: 118] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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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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Quddusi HM, Ramsey CM, Gonzalez-Pons JC, Henderson JJ, del Barco E, de Loubens G, Kent AD. On-chip integration of high-frequency electron paramagnetic resonance spectroscopy and Hall-effect magnetometry. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2008; 79:074703. [PMID: 18681725 DOI: 10.1063/1.2957616] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
A sensor that integrates high-sensitivity micro-Hall effect magnetometry and high-frequency electron paramagnetic resonance spectroscopy capabilities on a single semiconductor chip is presented. The Hall-effect magnetometer (HEM) was fabricated from a two-dimensional electron gas GaAsAlGaAs heterostructure in the form of a cross, with a 50 x 50 microm2 sensing area. A high-frequency microstrip resonator is coupled with two small gaps to a transmission line with a 50 Omega impedance. Different resonator lengths are used to obtain quasi-TEM fundamental resonant modes in the frequency range 10-30 GHz. The resonator is positioned on top of the active area of the HEM, where the magnetic field of the fundamental mode is largest, thus optimizing the conversion of microwave power into magnetic field at the sample position. The two gaps coupling the resonator and transmission lines are engineered differently--the gap to the microwave source is designed to optimize the loaded quality factor of the resonator (Q<or=150) while the gap for the transmitted signal is larger. This latter gap minimizes losses and prevents distortion of the resonance while enabling measurement of the transmitted signal. The large filling factor of the resonator permits sensitivities comparable to that of high-quality factor resonant cavities. The integrated sensor enables measurement of the magnetization response of micron scale samples upon application of microwave fields. In particular, the combined measurement of the magnetization change and the microwave power under cw microwave irradiation of single crystal of molecular magnets is used to determine of the energy relaxation time of the molecular spin states. In addition, real-time measurements of the magnetization dynamics upon application of fast microwave pulses are demonstrated.
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Affiliation(s)
- H M Quddusi
- Physics Department, University of Central Florida, Orlando, Florida 32816-2385, USA
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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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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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Hill S, Anderson N, Wilson A, Takahashi S, Petukhov K, Chakov N, Murugesu M, North J, Barco ED, Kent A, Dalal N, Christou G. A comparison between high-symmetry Mn12 single-molecule magnets in different ligand/solvent environments. Polyhedron 2005. [DOI: 10.1016/j.poly.2005.03.079] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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55Mn NMR spectra of Mn12 single-molecule magnets: Single crystal versus aligned powder studies. Polyhedron 2005. [DOI: 10.1016/j.poly.2005.03.117] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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He F, Tong ML, Chen XM. Synthesis, Structures, and Magnetic Properties of Heteronuclear Cu(II)−Ln(III) (Ln = La, Gd, or Tb) Complexes. Inorg Chem 2005; 44:8285-92. [PMID: 16270967 DOI: 10.1021/ic0507159] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Facile one-pot reactions led to the formations of dinuclear [CuLn(hmp)2(NO3)3(H2O)2] (Ln = Tb (1.Tb), Gd (1.Gd), or La (1.La)), and trinuclear [Cu2Ln(mmi)4(NO3)(H2O)2](ClO4)(NO3).2H2O (Ln = Tb (2.Tb) or Gd (2.Gd)) and [Cu2La(mmi)4(NO3)2(H2O)](ClO4).2H2O (2.La) with polydentate ligands 2-(hydroxymethyl)-pyridine and 2-hydroxymethyl-1-methyl-imidazole. In these complexes, each pair of Cu(II) and Ln(III) ions is linked by a double mu-alkoxo bridge. The temperature dependences of the magnetic susceptibilities of 1 and 2 were investigated in the range of 2-300 K. The dinuclear and trinuclear Cu-Gd complexes exhibit ferromagnetic interaction. The coupling constant J values in the heterodinuclear Cu-Gd complexes are correlated to values of the dihedral angles alpha between the two O-Cu-O and O-Gd-O fragments of the bridging CuO2Gd networks, with the largest J value associated with the smallest alpha value. The occurrence of a ferromagnetic interaction between Cu(II) and Gd(III) ions of the trinuclear entity is supported by the field dependence of the magnetization. The field dependence of the magnetization at 2 K of 1.Gd and 2.Gd confirms the nature of the ground state and of the Cu(II)-Gd(III) interaction, while alternating current susceptibility measurements demonstrates out-of-phase ac susceptibility signals of 1.Tb, which is the molecule-based magnetic material of the smallest nuclearity which exhibits frequency-dependent behavior within the 3d-4f mixed-metal systems.
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Affiliation(s)
- Feng He
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, PR China
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Miyasaka H, Clérac R. Synthetic Strategy for Rational Design of Single-Chain Magnets. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2005. [DOI: 10.1246/bcsj.78.1725] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Harter AG, Chakov NE, Roberts B, Achey R, Reyes A, Kuhns P, Christou G, Dalal NS. Single-Crystal 55Mn NMR Spectra of Two Mn12 Single-Molecule Magnets. Inorg Chem 2005; 44:2122-4. [PMID: 15792441 DOI: 10.1021/ic050048j] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The initial application is reported of single-crystal 55Mn NMR spectroscopy, and associated orientation dependence studies, to single-molecule magnets (SMMs). The studies were performed on two members of the Mn12 family of SMMs, [Mn12O12(O2CMe)16(H2O)4].2MeCO2H.4H2O (Mn12-Ac) and [Mn12O12(O2CCH2Br)16(H2O)4].4CH)Cl) (Mn12-BrAc). Single-crystal spectra give a dramatic improvement in the spectral resolution over oriented powder spectra, allowing the clear observation of quadrupolar splittings, the determination of quadrupole coupling parameters (e2qQ), and an assessment of the symmetry-lowering perturbation of the core of Mn12-Ac by hydrogen-bonding interactions with lattice solvate molecules of crystallization. The results emphasize the utility of single-crystal NMR studies to probe the cores of these magnetic molecules.
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Affiliation(s)
- Andrew G Harter
- Department of Chemistry and Biochemistry and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, USA
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