Studies of hysteresis and quantum tunnelling of the magnetisation in dysprosium(iii) single molecule magnets.

We report magnetic hysteresis studies of three Dy(iii) single-molecule magnets (SMMs). The three compounds are [Dy(tBuO)Cl(THF)5][BPh4] (1), [K(18-crown-6-ether)(THF)2][Dy(BIPM)2] (2, BIPM = C{PPh2NSiMe3}2), and [Dy(Cpttt)2][B(C6F5)4] (3), chosen as they have large energy barriers to magnetisation reversal of 665, 565, and 1223 cm-1, respectively. There are zero-field steps in the hysteresis loops of all three compounds, that remain in magnetically dilute samples and in samples that are isotopically enriched with 164Dy, which has no nuclear spin. These results demonstrate that neither dipolar fields nor nuclear hyperfine coupling are solely responsible for the quantum tunnelling of magnetisation at zero field. Analysing their vibrational modes, we find that the modes that most impact the first coordination sphere occur at the lowest energies for 1, at intermediate energies for 2 and at higher energies for 3, in correlation with their coercive fields. Therefore, we suggest that the efficiency of quantum tunnelling of magnetisation is related to molecular flexibility.

[1]  W. Wernsdorfer,et al.  Quantum tunnelling of the magnetisation in single-molecule magnet isotopologue dimers† †Electronic supplementary information (ESI) available. CCDC 1898383 and 1898384. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c9sc01062a , 2019, Chemical science.

[2]  O. Cador,et al.  Hyperfine coupling and slow magnetic relaxation in isotopically enriched DyIII mononuclear single-molecule magnets , 2019, Inorganic Chemistry Frontiers.

[3]  Fu-Sheng Guo,et al.  Magnetic hysteresis up to 80 kelvin in a dysprosium metallocene single-molecule magnet , 2018, Science.

[4]  B. Harvey,et al.  High-temperature magnetic blocking and magneto-structural correlations in a series of dysprosium(iii) metallocenium single-molecule magnets† †Electronic supplementary information (ESI) available: IR and NMR spectroscopy, synthesis of Y1–Y4, and magnetic characterization. Structures of compounds 1–4 , 2018, Chemical science.

[5]  Yan‐Zhen Zheng,et al.  Field- and temperature-dependent quantum tunnelling of the magnetisation in a large barrier single-molecule magnet , 2018, Nature Communications.

[6]  José J. Baldoví,et al.  Spin states, vibrations and spin relaxation in molecular nanomagnets and spin qubits: a critical perspective , 2018, Chemical science.

[7]  K. Bernot,et al.  Optimization of Magnetic Relaxation and Isotopic Enrichment in Dimeric DyIII Single‐Molecule Magnets , 2018 .

[8]  L. Chibotaru,et al.  Spin-lattice relaxation of magnetic centers in molecular crystals at low temperature , 2017, 1704.06699.

[9]  David P. Mills,et al.  Molecular magnetic hysteresis at 60 kelvin in dysprosocenium , 2017, Nature.

[10]  R. Sessoli.  Materials science: Magnetic molecules back in the race , 2017, Nature.

[11]  W. Wernsdorfer,et al.  Nuclear Spin Isomers: Engineering a Et4 N[DyPc2 ] Spin Qudit. , 2017, Angewandte Chemie.

[12]  E. Coronado,et al.  Determining Key Local Vibrations in the Relaxation of Molecular Spin Qubits and Single-Molecule Magnets. , 2017, The journal of physical chemistry letters.

[13]  B. le Guennic,et al.  Isotopically enriched polymorphs of dysprosium single molecule magnets. , 2017, Chemical communications.

[14]  S. Sanvito,et al.  The role of anharmonic phonons in under-barrier spin relaxation of single molecule magnets , 2017, Nature Communications.

[15]  Yan‐Zhen Zheng,et al.  On Approaching the Limit of Molecular Magnetic Anisotropy: A Near-Perfect Pentagonal Bipyramidal Dysprosium(III) Single-Molecule Magnet. , 2016, Angewandte Chemie.

[16]  N. Chilton,et al.  A Low-Symmetry Dysprosium Metallocene Single-Molecule Magnet with a High Anisotropy Barrier. , 2016, Angewandte Chemie.

[17]  W. Wernsdorfer,et al.  A Stable Pentagonal Bipyramidal Dy(III) Single-Ion Magnet with a Record Magnetization Reversal Barrier over 1000 K. , 2016, Journal of the American Chemical Society.

[18]  G. Rajaraman,et al.  An air-stable Dy(iii) single-ion magnet with high anisotropy barrier and blocking temperature , 2016, Chemical science.

[19]  Jiang Liu,et al.  Symmetry-Supported Magnetic Blocking at 20 K in Pentagonal Bipyramidal Dy(III) Single-Ion Magnets. , 2016, Journal of the American Chemical Society.

[20]  A. J. Blake,et al.  A monometallic lanthanide bis(methanediide) single molecule magnet with a large energy barrier and complex spin relaxation behaviour , 2015, Chemical science.

[21]  E. Coronado,et al.  Role of vibrations on decoherence in molecular spin qubits: The case of [Cu(mnt)$_2$]$^{2-}$ , 2015, 1512.05690.

[22]  J. van Slageren,et al.  Improving f-element single molecule magnets. , 2015, Chemical Society reviews.

[23]  K. Pedersen,et al.  Design of Single-Molecule Magnets: Insufficiency of the Anisotropy Barrier as the Sole Criterion. , 2015, Inorganic chemistry.

[24]  B. le Guennic,et al.  Magnetic memory in an isotopically enriched and magnetically isolated mononuclear dysprosium complex. , 2015, Angewandte Chemie.

[25]  A. Soncini,et al.  Single molecule magnetism in a family of mononuclear β-diketonate lanthanide(III) complexes: rationalization of magnetic anisotropy in complexes of low symmetry , 2013 .

[26]  Edwige Otero,et al.  Quantum tunnelling of the magnetization in a monolayer of oriented single-molecule magnets , 2010, Nature.

[27]  Gang Su,et al.  A mononuclear dysprosium complex featuring single-molecule-magnet behavior. , 2010, Angewandte Chemie.

[28]  W. Wernsdorfer,et al.  Quantum tunneling of magnetization in lanthanide single-molecule magnets: bis(phthalocyaninato)terbium and bis(phthalocyaninato)dysprosium anions. , 2005, Angewandte Chemie.

[29]  W. Wernsdorfer,et al.  Nuclear spin driven quantum tunneling of magnetization in a new lanthanide single-molecule magnet: bis(phthalocyaninato)holmium anion. , 2005, Journal of the American Chemical Society.

[30]  W. Wernsdorfer,et al.  Resonant Quantum Tunneling in a New Tetranuclear Iron(III)‐Based Single‐Molecule Magnet , 2004 .

[31]  W. Wernsdorfer,et al.  Single-molecule magnets: a large Mn30 molecular nanomagnet exhibiting quantum tunneling of magnetization. , 2004, Journal of the American Chemical Society.

[32]  R. Sessoli,et al.  Quantum tunneling of magnetization and related phenomena in molecular materials. , 2003, Angewandte Chemie.

[33]  D. Loss,et al.  Spin tunneling and phonon-assisted relaxation in Mn₁₂-acetate , 1999, cond-mat/9907154.

[34]  W. Wernsdorfer,et al.  Quantum phase interference and parity effects in magnetic molecular clusters , 1999, Science.

[35]  E. Chudnovsky,et al.  Thermally activated resonant magnetization tunneling in molecular magnets: Mn 12 Ac and others , 1997, cond-mat/9805057.

[36]  C. Sangregorio,et al.  QUANTUM TUNNELING OF THE MAGNETIZATION IN AN IRON CLUSTER NANOMAGNET , 1997 .

[37]  Friedman,et al.  Macroscopic measurement of resonant magnetization tunneling in high-spin molecules. , 1996, Physical review letters.

[38]  A. Caneschi,et al.  Magnetic bistability in a metal-ion cluster , 1993, Nature.