The Canted Antiferromagnetic Approach to Single-Chain Magnets

Abstract

The reaction of manganese(III) acetate meso-tetraphenylporphyrin with phenylphosphinic acid provides the one-dimensional compound of formula [Mn(TPP)O2PHPh] x H2O, which crystallizes in the monoclinic C2/c space group. The chain structure is generated by a glide plane resulting in Jahn-Teller elongation axes of the MnIII octahedra that alternate along the chain. The phenylphosphinate anion transmits a sizable antiferromagnetic exchange interaction that, combined with the easy axis magnetic anisotropy of the MnIII sites, gives rise to a canted antiferromagnetic arrangement of the spins. The static single-crystal magnetic properties have been analyzed with a classical Monte Carlo approach, and the best fit parameters for the exchange and single ion anisotropy are J = -0.68(4) K and D = -4.7(2) K, respectively (using the -2JS(i)S(j) formalism for the exchange). Below 5 K the single-crystal dynamics susceptibility reveals a frequency-dependent out-of-phase signal typical of single-chain magnets. The extracted relaxation time follows the Arrhenius law with delta = 36.8 K. The dynamic behavior has been rationalized and correlated to geometrical parameters of the structure. The contribution of the correlation length to the energy barrier has been investigated, and it has been found that the characteristic length that dominates the dynamics strongly exceeds the correlation length estimated from magnetic susceptibility.

Magnetic transition in α-NaCuPO4 with Cu-O chains

“…Single crystalline sample is necessary for verifying the possible spin-orbital coupling caused anisotropy of magnetic properties similar to other transition-metal systems. 3,[21][22][23] In addition, the large negative Curie temperature θ indicates an antiferromagnetic coupling, this is consistent with both the small value of saturated χ from χ -T curve and the minute resident moment from isothermal magnetization, as shown in Figs. 2(a) and 2(b).…”

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“…Ising-like anisotropy and weak inter-chain magnetic interactions give rise to slow relaxation and hysteresis loops of molecular origin, the behaviour observed also in SMM [1,45]. In some circumstances such systems can be considered as one-dimensional and modeled with quantum…”

Rekord‐Hartmagnete: Glauber‐Dynamik als Schlüssel zum Verständnis

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