THE MAGNETOSTRICTION OF GADOLINIUM AND HOLMIUM SINGLE CRYSTALS. Thesis
The magnetostriction of single crystals of gadolinium and holmium was measured. Maximum strains of 140 x 10/sup 6/ for gadolinium at 130 deg K and 3500 x 10/sup -6/ for holmium at 45 deg K were observed. An apparatus was designed and constructed to employ the standard strain gage techniques in the temperature range from 4.2 to 350 deg K. At 100 deg K the saturation magnetostriction constants for Gd were lambda /sub A/ = --96 x 10/sup -6/ lambda /sub B/ =--161 x 10/sup -6/ lambda /sub C/ =136 x 10/sub -6/ an d lambda /sub D/=21 x 10/sup -6/. The values indicate that gadolinium behaves like a normal ferromagnet, such as cobalt. An anomaly in the temperature dependence of the constants was observed at 218 deg K, and agrees with measurements of the anisotropy energy. The saturation magnetostriction constants of holmium could not be measured directly because of the high magnetic anisotropy. The strains in the principal crystallographic directions were observed as a function of the magnetic field applied along these directions. The shapes of the curves are explained on the basis of the spiral to ferromagnetic transition occurring in the magnetic structure. The unusually large magnetostriction reported for holmium is probably due to a combination of this magnetic transition and the high magnetic anisotropy. The dependence of principal strains on the direction of the maximum applied field (26 k0e.) was also measured in holmium. The unusual shapes of these curves are explained from considerations of the demagnetizing field and of the crystal symmetry. Using this model, three saturation constants were obtained for holmium; the magnitude of the constants at 4.2 deg K was about 2000 x 10/sup - 6/. (Dissertation Abstr., 24: No. 4, Oct. 1963.)
- Research Organization:
- Originating Research Org. not identified
- NSA Number:
- NSA-18-004280
- OSTI ID:
- 4125060
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
Similar Records
Magnetostriction of some rare earth-aluminum Laves phase compounds
Magnetic anisotropy of sputtered media induced by textured substrate