Ferromagnetic phases Curie temperature

All f 2Cu2ln indides order ferromagnetically with Curie temperatures between 26.7 and 85.5 K. Strong crystal field anisotropies result in Tc values that do not scale with the de Getmes frmction of the rare earth elements (Fisher et al., 1999). Dy2Cu2ln shows a second phase transition to an antiferromagnetic ground state at 7n = 22 K. 

The polymorphism of certain metals, iron the most important, was after centuries of study perceived to be the key to the hardening of steel. In the process of studying iron polymorphism, several decades were devoted to a red herring, as it proved this was the P-iron controversy. P-iron was for a long time regarded as a phase distinct from at-iron (Smith 1965) but eventually found to be merely the ferromagnetic form of ot-iron thus the supposed transition from P to a-iron was simply the Curie temperature, p-iron has disappeared from the iron-carbon phase diagram and all transformations are between a and y. 

F — ferromagnetic A — antiferromagnetic P — paramagnetic imp — impurity phase SR — spin reorientation Tq — Curie temperature Tn — Ndel temperature a and c — tetragonal lattice parameters, z — coordinate of B with c as its unit. 

Europium monoxide, EuO, is another ferromagnetic solid that may be used for studying the extrinsic field effect although the low Curie temperature restricts the usefulness of the results. Data are available (27) on two samples, one from the insulative part of the phase diagram with Tc = 69.3 1.0 K and surface 1.4 m2 g 1. (All samples of EuO are very sensitive to moist air and must be handled accordingly.) This sample is referred to below as EuO (ins). Another sample of EuO, from the conductive part of the diagram, had Tc = 129 3 K and surface 0.8 m2 g-1. This is referred to as EuO (con). 

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