Transport and tunneling measurements on thin films of heavy fermion compounds and related systems
High quality thin films of CeAl[sub 3], UBe[sub 13], and CeCu[sub 6] were prepared and used in magnetotransport experiments. The hexagonal crystal structure preferentially oriented with the c axis perpendicular to the Al[sub 2]O[sub 3] substrate. The measured resistivity of the films had the same behavior as that reported by other investigators for polycrystalline CeAl[sub 3], except for a sharper slope change at 6 K. Above 6 K, the magnetoresistance was isotropic, negative, and displayed H/T scaling. Scaling failed abruptly just below 6 K, and anisotropy began at the same temperature, demonstrating that only above 6 K is the scattering in CeAl[sub 3] similar to the scattering from a system of noninteracting Kondo ions. The resistivity maxima may represent a boundary in the (H,T) plane between coherent and incoherent behavior of the CeAl[sub 3] carriers. Between 1.8 K and 3.8 K, the positive magnetoresistance was proportional to (H/T)[sup 2], and also obeyed Kohler scaling. With the magnetic field in the CeAl[sub 3] basal plane the magnetoresistance remained negative until temperature was below 2 K. High-field Hall measurements in CeAl[sub 3] showed that the Hall resistivity reached its maximum value at a magnetic field B[sup *] = [kappa][sub B]T/g[mu][sub B] for temperatures above about 4K. Below 4 K, the same temperature at which H/T scaling began in magnetoresistance, the saturation field for the Hall resistivity increased as temperature decreased. The magnetoresistance and Hall measurements show the development of coherent behavior of the CeAl[sub 3] carriers between 4 K and 6 K. Hall measurements on a UBe[sub 13] film showed similar behavior to CeAl[sub 3], with the saturation field for the Hall resistivity beginning to increase below about 2 K. Hall measurements on a CeCu[sub 6] film did not show this behavior. The spin-orbit scattering rate in the superconducting portion of the film was found to be not greatly different from that in thin Al films.
- Research Organization:
- Massachusetts Inst. of Tech., Cambridge, MA (United States)
- OSTI ID:
- 7302821
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CERIUM COMPOUNDS
MAGNETORESISTANCE
TUNNEL EFFECT
URANIUM COMPOUNDS
ALUMINIUM COMPOUNDS
BERYLLIUM COMPOUNDS
COPPER COMPOUNDS
FERMIONS
HALL EFFECT
TEMPERATURE RANGE 0000-0013 K
THIN FILMS
TYPE-I SUPERCONDUCTORS
ACTINIDE COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
FILMS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
SUPERCONDUCTORS
TEMPERATURE RANGE
TRANSITION ELEMENT COMPOUNDS
360606* - Other Materials- Physical Properties- (1992-)
665430 - Other Topics in Quantum Fluids & Solids- (1992-)