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Durham e-Theses
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Measurements of the magnetic anisotropy of gadolinium

Roe, W. C. (1961) Measurements of the magnetic anisotropy of gadolinium. Doctoral thesis, Durham University.



Measurements of the magnetocrystalline anisotropy constants of gadolinium have been made using a torque method. Torque observations were made on a single crystal oblate spheroid of the material which contained the hexagonal axis in its plane. The system for measuring torque was null-reading and a counter - torque was provided by passing currents through a small coil running in an instrument magnet. Balancing was done automatically with a photocell feed-back amplifier system. Values of the anisotropy constants have been derived from observed torque curves by a least - squares fit to the theoretical curves. The process was carried out on the Perranti Pegasus computer. The anisotropy constants were obtained over the temperature range from the Curie point (~289 K) to 20 K and they are presented graphically. K(_1) found to be negative below ~ 235 K indicating an easy direction in the basal plane and the crystal only exhibits a uniaxial character above this temperature. The change in sign of prevents any comparison with the Zener theory.

Item Type:Thesis (Doctoral)
Award:Doctor of Philosophy
Thesis Date:1961
Copyright:Copyright of this thesis is held by the author
Deposited On:13 Nov 2013 16:14

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