MECHANISMS OF THE ELECTRICAL RESISTIVITY OF RARE EARTH ALLOYS AT LOW TEMPERATURES
The existence of complete solid solubility in the alloy systems Gd-- Lu, Tb- Lu, and Gd- Er was established by means of x-ray diffraction and electrical resistivity methods. The electrical resistivity was measured as a function of temperature from 4.2 to 310 deg K for twelve alloys in these systems and the data were analyzed to obtain the magnetic ordering temperatures, spin disorder resistivities, and the residual resistivities as a function of composition, and the temperature dependence of the resistivity in the low temperature region. The magnetic ordering temperatures were found to vary approximately linearly with composition, the spin disorder resistivities varied as (g - 1)/sup 2/ J(J + 1) with a general correlation between the (g - 1)/sup 2/ J(J + 1) value for an alloy and a metal with the same (g- 1)/sup 2/ J(J + 1) value, and the residual resistivities were found to follow Nordheim's rule. The residual resistivities of the Gd- Lu alloys were found to be about three times larger than would be expected from simple alloy disorder effects and the additional contribution was attributed to a disorder of magnetic ions in the lattice. This is another manifestation of the s-f interaction in rare earth metals previously found to influence the magnetic ordering temperatures, the spin disorder resistivities, and the superconducting transition temperature of lanthanum alloys. A series of dilute alloys of lutetium with various heavy rare earth metals as solutes was prepared, and the electrical resistivity of the alloys measured at 4.2 deg K to characterize this effect. The results provided the first experimental distinction between the spin dependence (g-1)/sup 2/ J(J + 1) predicted by de Gennes and Brout and Shul and the closely related spin dependence S(S + 1). The magnitude of the exchange integral was evaluated from the experimental data by use of Kasuya's equations and found to be 0.45 ev. Analysis of the published data on the pure metals showed the temperature dependence of the resistivity at low temperatures for Gd, Tb, and Dy to be in agreement with the T/sup 2/ dependence predicted from a spin wave model for a ferromagnetic metal and that of thulium to agree with the T/sup 4/ dependence predicted for an antiferromagnetic metal. The values of the parameter R, related to the Fermi surface area as described by Ziman, were calculated for the rare earth metals and compared with the published values for other metals. The variation of R within the heavy rare earth sub-group was found to be correlated with the c/a ratio for these metals. (Dissertation Abstr., 23: No. 3,
- Research Organization:
- Originating Research Org. not identified
- NSA Number:
- NSA-17-001996
- OSTI ID:
- 4769475
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
DYSPROSIUM
ELECTRIC CONDUCTIVITY
EQUATIONS
ERBIUM COMPOUNDS
FERMI LEVEL
FERROMAGNETIC MATERIALS
GADOLINIUM
GADOLINIUM COMPOUNDS
IMPURITIES
IONS
LATTICES
LOW TEMPERATURE
LUTETIUM COMPOUNDS
MAGNETISM
MEASURED VALUES
METALS
METALS, CERAMICS, AND OTHER MATERIALS
PARTICLE MODELS
PHASE DIAGRAMS
PREPARATION
RARE EARTHS
SOLID SOLUTIONS
SPIN
SPIN-LATTICE RELAXATION
STATISTICS
TERBIUM
TERBIUM COMPOUNDS
THULIUM
VARIATIONS
X RADIATION