Magnetostriction and magnetisation of praseodymium and some rare earth intermetallic compounds in pulsed magnetic fields
Magnetostriction and magnetisation of praseodymium and some rare earth intermetallic compounds in pulsed magnetic fields
The magnetostriction of polycrystalline cubic laves phase compounds of the form RFe,has been measured at temperatures in the range 5.3K - 300K in pulsed magnetic fields of up to 18 tesla. The specific compounds studied are GdFe2, HoFe2, ErFe, LuFe2 and CeFe2. The single crystal magnetostriction constants )i,oo, A, and the saturation magnetostriction as have been estimated for each compound. In the case of CeFe2, sharp increases in the magnetostriction curves were observed at fields of around 3 tesla and at temperatures below 150K; magnetisation measurements for CeFe2 have also been made on the same sample. The magnetisation curves show signs of a first order increase at the same fields but the change in magnetisation is much smaller than the change in magnetostriction. Magnetostriction and magnetisation of a single crystal of Praseodymium has been measured at pulsed fields up to 18 tesla and in the temperature range 3K - 78K. The measurements were made along all three principal axes and the transverse magnetostriction was also measured in each case. These results are analysed using a molecular field Hamiltonian. The dominant strain dependent interaction is shown to arise from the crystal field. Also no spontaneous magnetic ordering was observed down to - 3K. The magnetostriction of single crystal NdAI2 has been meac+aed in fields up to 2 tesla along the easy axis [ 100] and in fields of up to 18 tesla along the hard axis [ 1111. The measured strains are explained in terms of a single-ion Hamiltonian. The second order magnetoelastic coefficients are found to be Mi =- 31.7 K/ion and Me = 65.1 ± 7.5 K/ion. The measurements also show that the magnetic domains are unequally distributed among the six equivalent (100] easy directions. From a comparison of the longitudinal and transverse strains it was found that P = 0.48 t 0.03 (where P is the volume fraction of domains along the direction of measurements [ 100] ) and was independent of temperature for the crystal used.The magnetostriction of an ErZn single crystal was also measured between 5.7K and 78K using pulsed fields up to 18 tesla. The measurements along the easy axis [ 100] were performed on a (100) plane disc. The magnetostriction constant h, has been determined from the measurements along the easy' [1001 axis. The longitudinal and transverse strains show that the magnetic domains are equally distributed among the equivalent easy directions. Measurements along the hard axis [ 111] have not been successful.
University of Southampton
1979
Al-Rawi, Karim M
(1979)
Magnetostriction and magnetisation of praseodymium and some rare earth intermetallic compounds in pulsed magnetic fields.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The magnetostriction of polycrystalline cubic laves phase compounds of the form RFe,has been measured at temperatures in the range 5.3K - 300K in pulsed magnetic fields of up to 18 tesla. The specific compounds studied are GdFe2, HoFe2, ErFe, LuFe2 and CeFe2. The single crystal magnetostriction constants )i,oo, A, and the saturation magnetostriction as have been estimated for each compound. In the case of CeFe2, sharp increases in the magnetostriction curves were observed at fields of around 3 tesla and at temperatures below 150K; magnetisation measurements for CeFe2 have also been made on the same sample. The magnetisation curves show signs of a first order increase at the same fields but the change in magnetisation is much smaller than the change in magnetostriction. Magnetostriction and magnetisation of a single crystal of Praseodymium has been measured at pulsed fields up to 18 tesla and in the temperature range 3K - 78K. The measurements were made along all three principal axes and the transverse magnetostriction was also measured in each case. These results are analysed using a molecular field Hamiltonian. The dominant strain dependent interaction is shown to arise from the crystal field. Also no spontaneous magnetic ordering was observed down to - 3K. The magnetostriction of single crystal NdAI2 has been meac+aed in fields up to 2 tesla along the easy axis [ 100] and in fields of up to 18 tesla along the hard axis [ 1111. The measured strains are explained in terms of a single-ion Hamiltonian. The second order magnetoelastic coefficients are found to be Mi =- 31.7 K/ion and Me = 65.1 ± 7.5 K/ion. The measurements also show that the magnetic domains are unequally distributed among the six equivalent (100] easy directions. From a comparison of the longitudinal and transverse strains it was found that P = 0.48 t 0.03 (where P is the volume fraction of domains along the direction of measurements [ 100] ) and was independent of temperature for the crystal used.The magnetostriction of an ErZn single crystal was also measured between 5.7K and 78K using pulsed fields up to 18 tesla. The measurements along the easy axis [ 100] were performed on a (100) plane disc. The magnetostriction constant h, has been determined from the measurements along the easy' [1001 axis. The longitudinal and transverse strains show that the magnetic domains are equally distributed among the equivalent easy directions. Measurements along the hard axis [ 111] have not been successful.
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Published date: 1979
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Local EPrints ID: 462578
URI: http://eprints.soton.ac.uk/id/eprint/462578
PURE UUID: 7a456048-4b8c-4c64-ac0e-210fe37874b5
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Date deposited: 04 Jul 2022 19:25
Last modified: 04 Jul 2022 19:25
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Author:
Karim M Al-Rawi
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