Magnetoresistance of Oriented Gray Tin Single Crystals

Abstract

The electronic band structure of gray tin was investigated through magnetoresistance measurements on oriented $n$- and $p$-type single crystals at 77, 195, and 273°K. From these measurements the low-field magnetoresistance coefficients were evaluated. Magnetoresistance anisotropy was observed in $n$-type crystals at 195 and 273°K, but was not observed in either $n$- or $p$-type material at 77°K. Two possible explanations for the temperature-dependent anisotropy are proposed. The observed anisotropy satisfies, within the experimental uncertainty, the symmetry condition for ellipsoidal energy surfaces located along the [111] directions. Hall and conductivity measurements on samples used in the magnetoresistance study revealed a temperature-dependent mobility ratio greater than unity which supports the assumption that the magnetoresistance anisotropy observed in the intrinsic range should be assigned to the conduction band. Under this assumption and that of isotropy of lattice scattering, a lower limit of 2.3 is found for the electronic effective-mass anisotropy parameter.