Insulators magnetic behavior

Fluorides have long been known to provide useful materials for the checking and improvement of magnetic models1-4. Since they are generally strong insulators, their magnetic behavior can be thus interpretated more easily than that of oxides and sulfides, due to the absence of electronic delocalization. 

ROP of hydrocarbon-bridged [2]ferrocenophanes yields polyferrocenylethylenes 88 Ei=E2 = C 2 R = H or Me). Due to the more insulating hydrocarbon bridge in these materials, only slight communication between the iron centers is observed by cyclic voltammetry (redox coupling of A i/2 = 90mV). Nevertheless, cooperative magnetic behavior has been reported in TCNE-oxidized materials at low temperature. 

Insulators in which atoms have completely filled electronic shells, such as the noble elements or the purely ionic alkali halides (composed of atoms from columns I and VII of the Periodic Table) are actually the simplest cases the atoms or ions in these solids differ very little from isolated atoms or ions, because of the stability of the closed electronic shells. The presence of the crystal produces a very minor perturbation to the atomic configuration of electronic shells. The magnetic behavior of noble element solids and alkali halides predicted by the analysis at the individual atom or ion level is in excellent agreement with experimental measurements. 

In insulating solids whose magnetic behavior arises from individual ions or atoms, there is a common feature in the response to an external magnetic field H, known as the Curie law. This response is measured through the magnetic susceptibility, which according to the Curie law is inversely proportional to the temperature. The magnetic susceptibility is defined as... 

These expressions are known as the Lande g-factors in the context of the total angular momentum of atoms or ions with partially filled electronic shells, which are relevant to the magnetic behavior of insulators. 

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