Magnetic relaxation pathways in lanthanide single-molecule magnets.

Single-molecule magnets are compounds that exhibit magnetic bistability caused by an energy barrier for the reversal of magnetization (relaxation). Lanthanide compounds are proving promising as single-molecule magnets: recent studies show that terbium phthalocyanine complexes possess large energy barriers, and dysprosium and terbium complexes bridged by an N2(3-) radical ligand exhibit magnetic hysteresis up to 13 K. Magnetic relaxation is typically controlled by single-ion factors rather than magnetic exchange (whether one or more 4f ions are present) and proceeds through thermal relaxation of the lowest excited states. Here we report polylanthanide alkoxide cage complexes, and their doped diamagnetic yttrium analogues, in which competing relaxation pathways are observed and relaxation through the first excited state can be quenched. This leads to energy barriers for relaxation of magnetization that exceed 800 K. We investigated the factors at the lanthanide sites that govern this behaviour.

[1]  S. Koshihara,et al.  Lanthanide double-decker complexes functioning as magnets at the single-molecular level. , 2003, Journal of the American Chemical Society.

[2]  W. Wernsdorfer,et al.  Electronic read-out of a single nuclear spin using a molecular spin transistor , 2012, Nature.

[3]  Liviu F Chibotaru,et al.  Structure, magnetism, and theoretical study of a mixed-valence Co(II)3Co(III)4 heptanuclear wheel: lack of SMM behavior despite negative magnetic anisotropy. , 2008, Journal of the American Chemical Society.

[4]  Katie R. Meihaus,et al.  Dilution-induced slow magnetic relaxation and anomalous hysteresis in trigonal prismatic dysprosium(III) and uranium(III) complexes. , 2011, Inorganic chemistry.

[5]  A. Powell,et al.  Coexistence of distinct single-ion and exchange-based mechanisms for blocking of magnetization in a Co(II)2Dy(III)2 single-molecule magnet. , 2012, Angewandte Chemie.

[6]  Liviu F Chibotaru,et al.  Magnetic anisotropy in the excited states of low symmetry lanthanide complexes. , 2011, Physical chemistry chemical physics : PCCP.

[7]  W. Wernsdorfer,et al.  Supramolecular architectures for controlling slow magnetic relaxation in field-induced single-molecule magnets , 2012 .

[8]  Song Gao,et al.  Series of lanthanide organometallic single-ion magnets. , 2012, Inorganic chemistry.

[9]  J. Sesé,et al.  Lanthanoid single-ion magnets based on polyoxometalates with a 5-fold symmetry: the series [LnP5W30O110]12- (Ln3+ = Tb, Dy, Ho, Er, Tm, and Yb). , 2012, Journal of the American Chemical Society.

[10]  L. Chibotaru,et al.  A dinuclear cobalt(II) complex of calix[8]arenes exibiting strong magnetic anisotropy. , 2007, Dalton transactions.

[11]  W. Wernsdorfer,et al.  Single-molecule magnetism in cyclopentadienyl-dysprosium chlorides. , 2012, Chemical communications.

[12]  M. Yamashita,et al.  Molecular spintronics based on single-molecule magnets composed of multiple-decker phthalocyaninato terbium(III) complex. , 2012, Chemistry, an Asian journal.

[13]  E. Coronado,et al.  Mononuclear lanthanide single molecule magnets based on the polyoxometalates [Ln(W5O18)2]9- and [Ln(beta2-SiW11O39)2]13- (Ln(III) = Tb, Dy, Ho, Er, Tm, and Yb). , 2009, Inorganic chemistry.

[14]  L. Sorace,et al.  Lanthanides in molecular magnetism: old tools in a new field. , 2011, Chemical Society reviews.

[15]  W. Wernsdorfer,et al.  Dysprosium triangles showing single-molecule magnet behavior of thermally excited spin states. , 2006, Angewandte Chemie.

[16]  J. V. D. Broek,et al.  SPIN-LATTICE RELAXATION IN RARE EARTH ETHYSULPHATES. PART II , 1964 .

[17]  J. Long,et al.  Strong exchange and magnetic blocking in N₂³⁻-radical-bridged lanthanide complexes. , 2011, Nature chemistry.

[18]  J. V. D. Broek,et al.  Spin lattice relaxation in rare earth ethylsulphates. I , 1963 .

[19]  Ian J Hewitt,et al.  Spin chirality in a molecular dysprosium triangle: the archetype of the noncollinear ising model. , 2008, Physical review letters.

[20]  José J. Baldoví,et al.  Modeling the properties of lanthanoid single-ion magnets using an effective point-charge approach. , 2012, Dalton transactions.

[21]  J. Long,et al.  A N2(3-) radical-bridged terbium complex exhibiting magnetic hysteresis at 14 K. , 2011, Journal of the American Chemical Society.

[22]  F. Tuna,et al.  Single pyramid magnets: Dy5 pyramids with slow magnetic relaxation to 40 K. , 2011, Angewandte Chemie.

[23]  F. Tuna,et al.  Pentametallic lanthanide-alkoxide square-based pyramids: high energy barrier for thermal relaxation in a holmium single molecule magnet. , 2011, Chemical communications.

[24]  M Ruben,et al.  Supramolecular spin valves. , 2011, Nature Materials.

[25]  W. Wernsdorfer,et al.  Strong axiality and Ising exchange interaction suppress zero-field tunneling of magnetization of an asymmetric Dy2 single-molecule magnet. , 2011, Journal of the American Chemical Society.

[26]  A. Caneschi,et al.  Magnetic anisotropy in a dysprosium/DOTA single-molecule magnet: beyond simple magneto-structural correlations. , 2012, Angewandte Chemie.

[27]  Liviu F Chibotaru,et al.  The origin of nonmagnetic Kramers doublets in the ground state of dysprosium triangles: evidence for a toroidal magnetic moment. , 2008, Angewandte Chemie.

[28]  R. Orbach,et al.  Spin-Lattice Relaxation in Cerium Magnesium Nitrate at Liquid Helium Temperature: A New Process , 1961 .

[29]  D. Drung,et al.  Spin-lattice relaxation via quantum tunneling in an Er 3 + -polyoxometalate molecular magnet , 2010 .

[30]  J. Sesé,et al.  Lanthanoid Single‐Ion Magnets Based on Polyoxometalates with a 5‐Fold Symmetry: The Series [LnP5W30O110]12‐ (Ln3+: Tb, Dy, Ho, Er, Tm, and Yb). , 2013 .

[31]  R. Winpenny,et al.  Lanthanide single-molecule magnets. , 2013, Chemical reviews.

[32]  F. Tuna,et al.  Influence of the N-bridging ligand on magnetic relaxation in an organometallic dysprosium single-molecule magnet. , 2010, Chemistry.

[33]  S. Koshihara,et al.  Significant increase of the barrier energy for magnetization reversal of a single-4f-ionic single-molecule magnet by a longitudinal contraction of the coordination space. , 2007, Inorganic chemistry.

[34]  E. Coronado,et al.  Mononuclear Lanthanide Single Molecule Magnets Based on the Polyoxometalates [Ln(W5O18)2]19- and [Ln(β2-SiW11O39)2] 13- (LnIII: Tb, Dy, Ho, Er, Tm, and Yb). , 2009 .

[35]  W. Wernsdorfer,et al.  Single-molecule magnet behavior for an antiferromagnetically superexchange-coupled dinuclear dysprosium(III) complex. , 2011, Journal of the American Chemical Society.

[36]  E. Coronado,et al.  Influence of peripheral substitution on the magnetic behavior of single-ion magnets based on homo- and heteroleptic Tb(III) bis(phthalocyaninate). , 2013, Chemistry.