Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.623935
Title: The electrical and magnetic properties of some rare earth compounds
Author: Stewart, Andrew Morven
Awarding Body: University of London
Current Institution: Imperial College London
Date of Award: 1971
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Abstract:
The magnetic susceptibilities of the following intermetallic compounds of the Rare Earths and Zinc have been measured in the temperature range 2°K - 300°K: R2Zn17 for R = Gd, Tb, Dy, Ho, Er, Tm and RZn12 for R = Sm, Gd, Tb, Er, whose electrical resistivities have been measured as well. The susceptibilities of Yb2Zn17 and YbZn11 have been measured down to 77°K. The Rare Earth ions in all the compounds were found to be in a trivalent state, except for Yb, which was divalent. Apart from the two Yb compounds and SmZn12, the susceptibilities of the materials followed the Curie Weiss Law down to about 50°K, where deviations from the Law, due to crystal field effects, began to occur. Most of the compounds ordered in some type of coherent long-range antiferromagnetic mode, probably an incommensurate spiral, in the region of 50°K or below. Four of the R2Zn17 materials did not appear to order at temperatures down to 2°K. The two Gd compounds showed signs of an anomalous pseudo-ordering at temperatures well above their main ordering temperature, which has been observed before in other Gd compounds. A method of analysing the susceptibilities of Sm materials has been suggested, and using it, the properties of SmZn12 were found to be consistent with those of the other compounds. 3 The RZn12 resistivities were found to obey well-defined temperature power laws in the magnetically ordered regime. The magnetic resistivities of the Gd, Tb (and possibly Er) compounds go as T 5/21 and of SmZn12 as T5.2. The s-f coupling constant has been estimated in several ways, using a free electron band-structure, to be a few tenths of an eV in these materials. An experimental problem which has often afflicted users of the Faraday Magnetometer, is that when large magnetic moments are measured, it is found that lateral forces, which act on the magnetic specimen, cause the suspension to swing out of the vertical. The reasons for this have been analysed, and a particularly simple means of predicting when it will occur has been suggested.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.623935  DOI: Not available
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