Single chain magnets: where to from here?

Abstract

Single chain magnets (SCMs) are an interesting class of molecular polymeric materials displaying slow relaxation of the magnetization. They provide, at low temperatures, a magnetic hysteretic behaviour for a single polymeric chain. Although their behaviour evokes better-known magnetic nanoparticles and single-molecule magnets (SMMs), the similarity is mainly apparent. The fundamental differences in the physical origin of the magnetic behaviour offer perspectives that are still largely unexplored. Here we review the progress made in the synthesis, characterization and theoretical understanding of SCMs, highlighting differences and similarities with SMMs. For each of the points we then present a perspective of the advantages offered by this class of materials and we point out the main aspects that remain to be developed in the field.

Slow relaxation of the magnetization in Oximato-bridged heterobimetallic Copper(II)-Manganese(III) chains

“…Interestingly, ac susceptibility measurements of 1-3 show evidence of slow magnetic relaxation effects at very low temperatures as found for SCMs [Figures 6 (1), S10 (2) and S11 (3)]. [13][14][15][16][17] The out-of-phase magnetic susceptibility (c M ") becomes non-zero for temperatures below ca. 4.0 K and exhibits frequency-dependent maxima whose intensities decrease with decreasing frequency.…”

“…[13][14][15][16][17] Slow relaxation of the magnetization in a ferromagnetic Ising chain was first predicted by Glauber in 1965 and, after his theory, 18 the conditions to be fulfilled by a chain compound to be a SCM are: (i) the system must behave as a 1D Ising ferro-or ferrimagnet and (ii) the chains have to be well isolated from each other in order to hamper the transition to 3D magnetic ordering. Since this prediction, several families of SCMs have been prepared and magnetostructurally investigated, the bridging ligands being organic radicals, 17 single oximato/double phenoxo, 19 cyanido, 20 azido, 21 oxalato, 22 oxamato, 23 bis(2-pyridylcarbonyl) amidato, 24 carboxylato 25 and phosphato/phosphinato.…”

Combined first-principles and thermodynamic approach toM-nitronyl nitroxide(M= Co, Mn) spin helices

“…These anisotropic building blocks are coordinated to organic ligands that are functionalized in order to favor or shield the propagation of exchange interactions. This synthetic strategy naturally leads to the formation of magnetic systems with reduced dimensionality 8,9 , in which exchange paths may have finite connectivity (like in SMMs) or create one-(1D) or two-dimensional networks.…”

Local spin dynamics at low temperature in the slowly relaxing molecular chain [Dy(hfac)3{NIT(C6H4OPh)}]: A μ+ spin relaxation study

“…As a consequence, CoPhOMe became the prototype of a class of magnetic chains where, by changing the metal or the radical moieties, it is now possible to fine-tune the physical properties. Because of the slow relaxation of its magnetization at low temperature, CoPhOMe was classified as a single-chain magnet (SCM), 9,10 in analogy with singlemolecule magnets (SMMs). 1,9,11 The magnetic properties of such 1D systems were theoretically predicted by Glauber in the 1960s: 12 At low temperature, the magnetization relaxes slowly with a relaxation time that follows an Arrhenius law s ¼ s 0 Áexp(D/k B T), and no phase transition to threedimensional (3D) magnetic long-range order occurs before the magnetization blockage.…”

“…Because of the slow relaxation of its magnetization at low temperature, CoPhOMe was classified as a single-chain magnet (SCM), 9,10 in analogy with singlemolecule magnets (SMMs). 1,9,11 The magnetic properties of such 1D systems were theoretically predicted by Glauber in the 1960s: 12 At low temperature, the magnetization relaxes slowly with a relaxation time that follows an Arrhenius law s ¼ s 0 Áexp(D/k B T), and no phase transition to threedimensional (3D) magnetic long-range order occurs before the magnetization blockage. 10,13 Subsequently, several other compounds were shown to exhibit SCM behavior, 11,[14][15][16][17][18][19][20][21] with quantum effects influencing the magnetization dynamics at low temperatures.…”