Magnetism Curie type behavior

The magnetic susceptibility of p-[Fe(Cp )2][Pt(mnt)2] follow a Curie-Weiss behavior with 6 - 9.8 K. The dominant ferromagnetic interactions are assigned to the magnetic intrachain D+A interactions from the type I chains, as the contribution from the D+ [ A2]2 D+ unit chains is expected to respect only to the cations due to the strong dimerization of the anions, S - 0 for [A2]2. ... 

The compound TmAl3 has the Cu3Au-type cubic structure. Magnetic measurements by Buschow (80) showed that this compound exhibits Curie-Weiss behavior at high temperatures but shows temperature-independent susceptibility at low temper-... 

Ehrenfest s concept of the discontinuities at the transition point was that the discontinuities were finite, similar to the discontinuities in the entropy and volume for first-order transitions. Only one second-order transition, that of superconductors in zero magnetic field, has been found which is of this type. The others, such as the transition between liquid helium-I and liquid helium-II, the Curie point, the order-disorder transition in some alloys, and transition in certain crystals due to rotational phenomena all have discontinuities that are large and may be infinite. Such discontinuities are particularly evident in the behavior of the heat capacity at constant pressure in the region of the transition temperature. The curve of the heat capacity as a function of the temperature has the general form of the Greek letter lambda and, hence, the points are called lambda points. Except for liquid helium, the effect of pressure on the transition temperature is very small. The behavior of systems at these second-order transitions is not completely known, and further thermodynamic treatment must be based on molecular and statistical concepts. These concepts are beyond the scope of this book, and no further discussion of second-order transitions is given. 

The magnetic susceptibility versus temperature behavior is typically interpreted using three types of plots. One is the so-called Curie-Weiss plot of 1/x versus T (Fig. 2). The Brillouin form of magnetization given earlier reduces to a simple form when H T in energy terms the Curie law (Equation (3)), in... 

The compound with pentacyanopropenide was found to possess a ID-DAD A structure in the solid state, but the main magnetic behavior was of the antiferromagnetic type, as the material obeys the Curie-Weiss law (y = C/T — 0) governing the temperature dependence of the magnetic susceptibility with 0 = —1.2 K (compare with 0 = -1-30 K for [FeCpf] [TCNE] , above 60 K) [28]. 

A) and an approximate side-to-side arrangement of the cations is observed. This type of structure is responsible for the observed paramagnetic behavior of this material, which follows the Curie law (0 0) over the whole temperature range for which magnetic susceptibility measurements have been carried out. 

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