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
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360606* -- Other Materials-- Physical Properties-- (1992-)
665430 -- Other Topics in Quantum Fluids & Solids-- (1992-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ACTINIDE COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
BERYLLIUM COMPOUNDS
CERIUM COMPOUNDS
COPPER COMPOUNDS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
FERMIONS
FILMS
HALL EFFECT
MAGNETORESISTANCE
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
SUPERCONDUCTORS
TEMPERATURE RANGE
TEMPERATURE RANGE 0000-0013 K
THIN FILMS
TRANSITION ELEMENT COMPOUNDS
TUNNEL EFFECT
TYPE-I SUPERCONDUCTORS
URANIUM COMPOUNDS