Thermal magnetoresistance of potassium

Technical Report · Thu Jan 01 04:00:00 EST 1976

DOI:https://doi.org/10.2172/7349675· OSTI ID:7349675

Newrock, R. S.; Maxfield, B. W.

The thermal magnetoresistance of single and polycrystalline specimens of potassium having residual resistance ratios (RRR) ranging from 1100 to 5300, was measured between 2 and 9/sup 0/K for magnetic fields up to 1.8T. The observed thermal magnetoresistance cannot be understood on the basis of either semiclassical theories or from the electrical magnetoresistance and the Weidmann--Franz law. The thermal magnetoresistance, W(T,H), is given reasonably well by W(T,H)T = W(T,O)T + AH + BH/sup 2/ where both A and B are temperature-dependent coefficients. The results show that A = A/sub 0/ + A/sub 1/T/sup 3/ while B(T) cannot be expressed as any simple power law. A/sub 0/ is quite dependent upon the RRR while A/sub 1/ is independent of the RRR. Two interesting relations were found between corresponding coefficients in the electrical and thermal magnetoresistance: (1) the Weidmann--Franz law relates A/sub 0/ to the Kohler slope of the electrical magnetoresistance and (2) the temperature-dependent portions of the electrical and thermal Kohler slopes are both proportional to the electron--phonon scattering contribution to the corresponding zero-field resistance. This is evidence that inelastic scattering is very important in determining the temperature-dependent linear magnetoresistances. Part, but by no means all, of the quadratic thermal resistance is accounted for by lattice thermal conduction. After subtracting the lattice contribution, the Lorentz ratio is still strongly field dependent, decreasing with increasing field. The general conclusion is made that at least a portion of the anomalous electrical and thermal magnetoresistances is due to intrinsic causes and not inhomogeneities or other macroscopic defects.

• Research Organization: Cincinnati Univ., OH (USA). Dept. of Physics; Cornell Univ., Ithaca, NY (USA). Lab. of Atomic and Solid State Physics
• OSTI ID: 7349675
• Report Number(s): COO-3150-36
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ALKALI METALS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELEMENTS
MAGNETIC FIELDS
MAGNETORESISTANCE
METALS
PHYSICAL PROPERTIES
POTASSIUM
TEMPERATURE DEPENDENCE
THERMAL CONDUCTIVITY
THERMODYNAMIC PROPERTIES
ULTRALOW TEMPERATURE