Measurement of the Quantum Tunneling Gap in a Dysprosocenium Single-Molecule Magnet

Abstract

We perform magnetization sweeps on the high-performing single-molecule magnet [Dy­(Cpttt)2]­[B­(C6F5)4] (Cpttt = C5H2 t Bu3-1,2,4; t Bu = C­(CH3)3) to determine the quantum tunneling gap of the ground-state avoided crossing at zero-field, finding a value on the order of 10–7 cm–1. In addition to the pure crystalline material, we also measure the tunnel splitting of [Dy­(Cpttt)2]­[B­(C6F5)4] dissolved in dichloromethane (DCM) and 1,2-difluorobenzene (DFB). We find that concentrations of 200 or 100 mM [Dy­(Cpttt)2]­[B­(C6F5)4] in these solvents increases the size of the tunneling gap compared to the pure sample, despite a similarity in the strength of the dipolar fields, indicating that either a structural or vibrational change due to the environment increases quantum tunneling rates.

Solvation/desolvation induced reversible distortion change and switching between spin crossover and single molecular magnet behaviour in a cobalt(ii) complex

“…S14 †). [83][84][85] Consequently, the α values, which determine the width of the distribution of relaxation times at 1000 Oe and HF at 3000 Oe, appear within a small range (Tables S5 and S6, † α < 0.3), supporting a single relaxation process. However, the α values at LF below 3000 Oe and above 2.2 K were high owing to the disappearance of their peaks at higher temperatures.…”

Ferrocenyl-substituted nitronyl nitroxide in the design of one-dimensional magnets

“…The magnetic relaxation times (τ) for [Co(hfac) 2 L] n were obtained by simultaneous fitting of χ′ and χ″ frequency dependencies using the generalized Debye model. 56,57 The relaxation times follow an Arrhenius thermal activation behaviour τ −1 = τ 0 −1 •exp(−Δτ/T ) with an activation energy barrier of Δτ = 190(20) cm −1 and τ 0 = 10 −11 -10 −12 s (Fig. 5d).…”

High-Pressure Investigation of a Five-Coordinate Dy Single-Molecule Magnet

“…14,33,35 The causes of transverse magnetic anisotropy can be molecular vibrations, spin−spin and spin−nuclear coupling with the neighboring magnetic centers. 33,34 The slight variation of the Dy−Dy distances with external pressure can also influence the dipolar fields around a Dy center and consequently the QTM relaxation times. 21 To determine the variation of QTM relaxation times arising from changes in the effective dipolar field, or due to something more intrinsic, we have performed classical simulations of the dipolar magnetic field at each pressure point.…”

“…Among Dy­(III) SMMs, even though QTM is forbidden between isolated KDs by Kramers theorem of time-reversal symmetry, transverse magnetic anisotropy can introduce interstate mixing and facilitate magnetic relaxation via QTM. − Hence QTM is a primary factor that determines the SMM behavior of Dy­(III) SMMs that show lower blocking temperatures than what is expected from their high U eff values. ,, The causes of transverse magnetic anisotropy can be molecular vibrations, spin–spin and spin–nuclear coupling with the neighboring magnetic centers. , The slight variation of the Dy–Dy distances with external pressure can also influence the dipolar fields around a Dy center and consequently the QTM relaxation times . To determine the variation of QTM relaxation times arising from changes in the effective dipolar field, or due to something more intrinsic, we have performed classical simulations of the dipolar magnetic field at each pressure point.…”