HALL EFFECT IN Lu, Yb, Tm, AND Sm

The Hall effect in Lu, Yb, Tm, and Sm was studied as a function of temperature for the temperature range 40 to 320 deg K in a magnetic field of 5500 oe. The Hall coefficient for Yb is positive, while the Hall coefficients for Lu and Tm are negative. Sm has a negative Hall effect at room temperature, but at lower temperatures the sign apparently changes. (auth) Employing Born's theory of crystal lattices, the elastic constants of fluorspar were evaluated theoretically. Besides the coulomb forces, repulsive forces between nearest neighbor calcium and fluorine atoms and fluorine --fluorine atoms were assumed and the constants of the repulsive energy were evaluated from the equilibrium condition, the experimentally dctermined compressibility and the principal Raman frequency of fluorspar. The experimental values of c/sub 11/, c/sub 12/, and c/ sub 44/ are in fair agreement with the theoretically calculated values. Born's theory gives the sign of c/sub 12/--c/sub 4/ for fluorspar correctly but the theoretically calculated value of c/sub 12/-c/sub 44/is only about half the experimentally observed value. (auth)