Synthesis, crystal structure and magnetic properties of a new [ZnII6DyIII6] dodecanuclear motif

Pentanuclear Spirocyclic Ni4Ln Derivatives: Field Induced Slow Magnetic Relaxation in the Dysprosium and Erbium Analogues

“…A good fit was achieved with energies barriers of the relaxation of the magnetization ( U eff ) of 25.57 (±1.75) cm –1 (5662 Hz); 25.90 (±1.34) cm –1 (6838 Hz); 25.39 (±1.04) cm –1 (8274 Hz) and 23.61 (±1.12) cm –1 (9984 Hz), being the average U eff = 25.12 (±1.31) cm –1 and an average τ 0 = 4.36 (±0.93) × 10 –9 s –1 (Figure ). The values obtained of the fit of the ac data are in the order of magnitude of other Schiff base 3d‐4f systems, reported previously in the literature , . The spin relaxation of this system take place by QTM within the first excited‐state doublets, since the Dy III centre has D 2 d symmetry .…”

“…The values obtained of the fit of the ac data are in the order of magnitude of other Schiff base 3d-4f systems, reported previously in the literature. [82,83] The spin relaxation of this system take place by QTM within the first excited-state doublets, since the Dy III centre has D 2d symmetry. [84] This is in accordance to the fact that many Dy III systems with D 2d symmetry only present maxima under an applied dc-field.…”

Metal–Organic Frameworks as Playgrounds for Reticulate Single-Molecule Magnets

“…The absence of maxima in the χ M ″ curves has precluded analysis of the out-of-phase signals with commonly use methods. − However, we believe that only one characteristic time for the SMM relaxation, which corresponds to a Debye process with one activation energy ( E a ), is possible to express the relaxation time (τ) as the Arrhenius law τ = τ 0 exp­( E a / k B T ) . Then, considering that χ M ″/χ M ′ = 2πυτ (υ is the experimental ac-field-exciting frequency), it is possible to roughly evaluate the values of E a and τ 0 through the expression ln­(χ M ″/χ M ′) = ln­(πυτ) + E a / k B T .…”

“…94−96 However, we believe that only one characteristic time for the SMM relaxation, which corresponds to a Debye process with one activation energy (E a ), is possible to express the relaxation time (τ) as the Arrhenius law τ = τ 0 exp(E a / k B T). 97 Then, considering that χ M ″/χ M ′ = 2πυτ (υ is the experimental ac-field-exciting frequency), it is possible to roughly evaluate the values of E a and τ 0 through the expression ln(χ M ″/χ M ′) = ln(πυτ) + E a /k B T. The values obtained for E a and τ 0 were 3.24(4) (3) and 9.90 (7) (5) cm −1 and 3.2(2) × 10 −6 (3) and × 10 −7 (5) s, respectively, which are similar to those of other SMMs previously analyzed through this method (insets, Figures 9 and 10). (11) Å, V = 48940(44) Å 3 .…”

“…[94][95][96] However, taking the assumption that the SMM relaxation has just one characteristic time -corresponding to a Debye relaxation process driven by one activation energy (Ea)-the relaxation time () may be written in terms of the Arrhenius law  = 0 exp (Ea/kBT). 97 Then, taking into account that χM"/χM' = 2 where is the experimental ac field exciting frequency, it is possible to roughly evaluate the values of Ea and 0 through the expression ln(χM"/χM') = ln() + Ea/kBT. The values obtained for Ea and 0 were 3.24(4) (3) and 9.90 (7) (5) cm -1 and 3.2(2) x 10 -6 (3) and 1.5(2) x 10 -7 (5) s, respectively, which are similar to the ones of other SMMs previously analyzed through this method (inset Figures 9 and 10).…”