Multiple Magnetization Reversal Channels Observed in a 3d-4f Single Molecule Magnet

Abstract

Abstract:The present study discusses the magnetic dynamics of a previously reported cyanide bridged 3d-4f dinuclear Dy III Co III complex. Following the axial anisotropy suggested by previous Electron Paramagnetic Resonance spectroscopy (EPR) analysis, the complex turned out to show slow relaxation of the magnetization at cryogenic temperature, and this was studied in different temperature and field regimes. The existence of multichannel relaxation pathways that reverse the magnetization was clearly disclosed: a tentative analysis suggested that these channels can be triggered and controlled as a function of applied static magnetic field and temperature. Persistent evidence of a temperature independent process even at higher fields, attributable to quantum tunneling, is discussed, while the temperature dependent dynamics is apparently governed by an Orbach process. The broad distribution of relaxation rates evidenced by the ac susceptibility measurements suggest a relevant role of the intermolecular interactions in this system.

Field-Induced Slow Relaxation in a Dinuclear Dysprosium(III) Complex Based on 3-Methoxycinnamic Acid

“…The occurrence of multiple relaxations has been widely observed in genuine field-induced lanthanide based SMM even in the case of one crystallographically relaxing lanthanide ion [11,13,36]. For 1, the observed plateau at low frequencies most likely arises from a collective behavior resulting from strong dipolar interactions or from the occurrence of a hydrogen bonded network, as evidenced by the crystal structure analysis.…”

Magneto-Luminescence Correlation in the Textbook Dysprosium(III) Nitrate Single-Ion Magnet

“…Multiple relaxation processes have been widely observed in lanthanide zero-field or field induced SIMs [3,27,28]. For 1, the independent frequency process observed in the low frequency range most likely arises from a collective behavior resulting from strong dipolar interactions or hydrogen bond network involving water molecules.…”

Multiple relaxation times in single-molecule magnets

“…According to the generalized Debye model [6][7][8], the relaxation time τ is associated with the inverse of the frequency at which the out-of-phase susceptibility χ (ω) attains its maximum, τ = 1/ω max . However, this interpretation of the ac susceptibility becomes confusing with the emergence of lanthanide-based SMMs [9][10][11][12], where more and more observations of two maxima in χ (ω) are reported in polynuclear compounds [13][14][15][16][17][18][19][20]. This phenomenon is usually explained by associating each relaxation time to a distinct relaxation pathway at magnetic centers of different kinds in these complexes [13][14][15][16][17][18][19][20].…”