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Magnetic Anisotropy, Magneto–Structural Correlations and Mechanism of Magnetic Relaxation in {Dy III N 8 } Complexes: A Theoretical Perspective
Author(s) -
Gupta Tulika,
Rajaraman Gopalan
Publication year - 2018
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201800350
Subject(s) - chemistry , magnetization , ground state , anisotropy , magnetic anisotropy , ab initio quantum chemistry methods , ab initio , relaxation (psychology) , ion , electron paramagnetic resonance , condensed matter physics , crystallography , nuclear magnetic resonance , magnetic field , atomic physics , molecule , physics , psychology , social psychology , organic chemistry , quantum mechanics
Ab initio CASSCF calculations have been undertaken to probe the origin of magnetic anisotropy in two structurally related {Dy III N 8 } SIMs {[Dy(tmtaa) 2 ] – and [K(DME) 2 ][Dy(tmtaa) 2 ]; 1 and 2 , respectively}. Our calculations reveal that complex 1 possesses a larger barrier for reorientation of magnetization ( U cal ) than does 2 . This is essentially due to the intrusion of K + ions, which distort the geometry and the donor abilities of the ligands in complex 2 , compared with 1 . Moreover, the ligand field around Dy III was found to stabilize |m J > = |±13/2> as the ground state, with stronger mixing by other |m J > levels. This corresponds to the observation of large g xx and g yy values at the ground state, leading to an efficient QTM process and very fast relaxation. The computed ground‐state |m J > levels and the estimated g tensors for both complexes are in agreement with experimental results obtained from magnetic and EPR spectroscopic studies. In addition, we have developed various magneto–structural correlations for complexes 1 and 2 , in order to understand how small structural distortions are likely to influence the magnetic anisotropy. These correlations offer clues to enhancing the barrier height for magnetization reversal in {Dy III N 8 } complexes.