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Durham e-Theses
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Investigations into the magnetic properties of rare earth compounds

Ellis, H. D. (1967) Investigations into the magnetic properties of rare earth compounds. Doctoral thesis, Durham University.



Magnetic measurements have been carried out on compounds of the form Gd(_x)Y(_1-x)Co(_2), where x varies from 1 to 0. The measurements were carried out over a wide range of temperatures and applied magnetic fields on a vibrating sample magnetometer. The results show that these compounds with high gadolinium content are strong magnetic, and their Curie points range from 400ºK inGdCo(_2) down to near zero for x 0.l. The compound YCo(_2) is shown to be antiferromagnetic, with, a Keel point of 190 K. The magnetisation versus temperature results show an anomaly im the form of a "kink" in the curves for those compounds, with x greater than 0.33, and the presence of this kink is shown to be dependent on the strength of the applied magnetic field, a minimum, or critical field Being required before the anomaly appears. The model proposed to explain, this: behaviour is. an adaptation of one proposed by Lotgering, for which an. antiferromagnetic Gd-Go coupling, an antiferromagnetic Co-Co coupling, and a ferromagnetic Cd-Cd coupling are required, Given these conditions, it is shown that a triangular configurations of moments can; exist, in which the Gd moments lie parallel to the applied magnetic field, and the cobalt moments; lie antiparallel to the applied field, but tilted alternately right and left at an angle so as to form a triangle with the Gd moment. It is shown, that such, a condition cam exist only; below a certain critical temperature, and at fields above a certain critical value. In all respects this model appears to fit the observed results well, but confirmation of the existence of such a configuration not only: in these compounds, but probably: in rare-earth - (cobalt)(_2) and rare-earth - (iron)(_2) compounds also, must await neutron diffraction measurements with a moderately high magnetic field applied to the specimens.

Item Type:Thesis (Doctoral)
Award:Doctor of Philosophy
Thesis Date:1967
Copyright:Copyright of this thesis is held by the author
Deposited On:13 Nov 2013 15:36

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