Magnetism: antiferromagnetic chains

Table 1 Coefficients for the expansion of the molar magnetic susceptibility of the X = 1 /2 Heisenberg antiferromagnetic chain in equation (36). This expression is valid over the temperature range 0.01 < r/ 27 < 5...

In the crystal structures of nitronyl nitroxide 27 and iminyl nitroxide 28 (Figure 6), magnetic linear chains along the r-axis have been observed when R is H. These solids exhibit strong antiferromagnetism. In contrast, Cl substitutions in both radicals result in a less favorable geometry for intermolecular spin interactions <1997JOC8854>. 

The first structural and magnetic properties of copper(II) chloranilate appeared in 1960 This compound behaves as a S = 1/2 antiferromagnetic chain with a J value around —24cm . The coupling constant J is defined by the phenomenological Heisenberg Hamiltonian ... 

SPECIFIC HEAT OF THREE MAGNETIC LINEAR-CHAIN ANTIFERROMAGNETS. 

C.S.15 magnetic linear chain system, antiferromagnetic principal magnetic susceptibilities measured along ... 

An interesting feature of the spin system of this LB film was revealed by temperature dependent ESR measurements [76-78]. The temperature dependence of spin susceptibility of the LB film together with that of powder sample is shown in Figure 14.10. The magnetic properties in both LB and powder state were adequately explained by the random-exchange Heisenberg antiferromagnetic chain (REHAC) model. 

Concerning molecule-based magnets, the first spin-ladder was synthesized (/ -EPYNN)[Ni (dmit)2] (/ -EPYNN = / -7V-ethylpyridinium o-nitronyl nitroxide). Within the crystal lattice, the radical cation /7-EPYNN units are arranged in ID chains with ferromagnetic interactions. The chains of [Ni(dmit)2] moieties in the ladder formation exhibit coexistent antiferromagnetic interactions.1031,1032... 

---