Broken Symmetry and Ordering Phenomena in Spin Crossover Solids
Event details
| Date | 16.10.2014 |
| Hour | 16:30 › 17:30 |
| Speaker |
Dr Grace Morgan School of Chemistry and Chemical Biology, University College Dublin, Ireland. |
| Location | |
| Category | Conferences - Seminars |
Spontaneous symmetry breaking[1] governs many transitions in nature, in condensed matter and in particle physics. In the last decade it has also emerged as a structural feature in many examples of two-step spin crossover (SCO) in FeII,[2], FeIII[3] and CoII.[4] In correlated magnetic materials the underlying driving force for such structural phase transitions is often magnetic frustration, such as the ferrimagnetic ordering observed in CsCoCl3,[5] but despite the increasing number of symmetry breaking events in SCO complexes the origin of the phenomenon in these systems is not well understood. Here we present some new examples of symmetry breaking two-step SCO transitions in FeIII and in the less well-studied MnIII ion,[5]-[7] and examine the nature of the ordering in the intermediate phase. In particular we examine the nature and direction of the Jahn-Teller distortion in the S=2 state of the MnIII examples and how this affects the crystal packing. We also examine magneto- optical phenomena at low temperature and and how these correlate with the broken symmetry phase in some FeIII examples.
[1] P. W. Anderson, More is Different, Science 1972, 177, 393-396.
[2] N. Brefuel, H. Watanabe, L. Toupet, J. Come, N. Matsumoto, E. Collet, K. Tanaka, J. –P. Tuchagues, Concerted Spin Crossover and Symmetry Breaking Yield Three Thermally and One Light-Induced Crystallographic Phases of a Molecular Material, Angew. Chem. Int. Ed. Eng., 2009, 48, 9304-9307
[3] M. Griffin, S. Shakespeare, H. J. Shepherd, C. J. Harding, J. –F. Létard, C. Desplanches, A. E. Goeta, J. A. K. Howard,A.K.Powell,V.Mereacre,Y.Garcia,A.D.Naik,H.Müller-Bunz,G.G.Morgan, SymmetryBreaking Spin State Transition in Iron(III), Angew. Chem. Int. Ed. Eng., 2011, 50, 896-900.
[4] a) M. G. Cowan, J. Olguín, S. Narayanaswamy, J. L. Tallon, S. Brooker, Reversible Switching of a Cobalt Complex by Thermal, Pressure and Electrochemical Stimuli: Abrupt, Complete, Hysteretic Spin Crossover, J. Am. Chem. Soc., 2012, 134, 2892-2894.
[5] A Manganese(III) Complex that Exhibits Spin Crossover Triggered by Geometric Tuning, G. G. Morgan, K. D. Murnaghan, H. Müller-Bunz, V. McKee and C. J. Harding, Angew. Chem. Int. Ed., 2006, 45, 7172-7175.
[6] Cooperative Spin Transition in a Mononuclear Manganese(III) Complex, P. N. Martinho, B. Gildea, M. M. Harris, T. Lemma, A. D. Naik, H. Muller-Bunz, T. E. Keyes, Y. Garcia and G. G. Morgan, Angew. Chem. Int. Ed., 2012, 51, 12597-12601.
[7] Lattice Effects on the Spin Crossover Profile of a Manganese(III) Cation, K. Pandurangan, B. Gildea, C. Murray, C. J. Harding, H. Müller-Bunz and G. G. Morgan, Chem. Eur. J., 2012, 18, 2021-2029.
[1] P. W. Anderson, More is Different, Science 1972, 177, 393-396.
[2] N. Brefuel, H. Watanabe, L. Toupet, J. Come, N. Matsumoto, E. Collet, K. Tanaka, J. –P. Tuchagues, Concerted Spin Crossover and Symmetry Breaking Yield Three Thermally and One Light-Induced Crystallographic Phases of a Molecular Material, Angew. Chem. Int. Ed. Eng., 2009, 48, 9304-9307
[3] M. Griffin, S. Shakespeare, H. J. Shepherd, C. J. Harding, J. –F. Létard, C. Desplanches, A. E. Goeta, J. A. K. Howard,A.K.Powell,V.Mereacre,Y.Garcia,A.D.Naik,H.Müller-Bunz,G.G.Morgan, SymmetryBreaking Spin State Transition in Iron(III), Angew. Chem. Int. Ed. Eng., 2011, 50, 896-900.
[4] a) M. G. Cowan, J. Olguín, S. Narayanaswamy, J. L. Tallon, S. Brooker, Reversible Switching of a Cobalt Complex by Thermal, Pressure and Electrochemical Stimuli: Abrupt, Complete, Hysteretic Spin Crossover, J. Am. Chem. Soc., 2012, 134, 2892-2894.
[5] A Manganese(III) Complex that Exhibits Spin Crossover Triggered by Geometric Tuning, G. G. Morgan, K. D. Murnaghan, H. Müller-Bunz, V. McKee and C. J. Harding, Angew. Chem. Int. Ed., 2006, 45, 7172-7175.
[6] Cooperative Spin Transition in a Mononuclear Manganese(III) Complex, P. N. Martinho, B. Gildea, M. M. Harris, T. Lemma, A. D. Naik, H. Muller-Bunz, T. E. Keyes, Y. Garcia and G. G. Morgan, Angew. Chem. Int. Ed., 2012, 51, 12597-12601.
[7] Lattice Effects on the Spin Crossover Profile of a Manganese(III) Cation, K. Pandurangan, B. Gildea, C. Murray, C. J. Harding, H. Müller-Bunz and G. G. Morgan, Chem. Eur. J., 2012, 18, 2021-2029.
Practical information
- General public
- Free
Organizer
- Dr Frank van Mourik