Weak-Field Magnetoresistance inp-Type Lead Telluride at Room Temperature and 77°K

Abstract

The weak-field magnetoresistance of six single crystals of $p$-type PbTe was measured at room temperature and 77\ifmmode^\circ\else\textdegree\fi{}K. The general predictions of weak-field theory were precisely obeyed in the range of magnetic-field intensities for which the theory should apply. In stronger fields at 77\ifmmode^\circ\else\textdegree\fi{}K, deviations from weak-field behavior of three types were observed which agree with the Gold-Roth theory of magnetoresistance at arbitrary magnetic-field strengths. The weak-field data at both temperatures conformed very closely to the $〈111〉$ ellipsoid-of-revolution multivalley model with values of the mass and scattering-time anisotropy parameter $K$ of 4.7 (room temperature) and 4.2 (77\ifmmode^\circ\else\textdegree\fi{}K), and with values of the statistical-scattering factor $G$ of 1.17 (room temperature) and 1.016 (77\ifmmode^\circ\else\textdegree\fi{}K). The dependence of the magnetoresistance at 77\ifmmode^\circ\else\textdegree\fi{}K on the Fermi level was used to make a rough calculation of the effective-mass components of the carriers in $p$-type PbTe which led to a total density-of-states effective mass of 0.16 times the free electron mass. Some preliminary room-temperature magnetoresistance data on $n$-type PbTe and on PbS and PbSe were also obtained which revealed that the longitudinal magnetoresistance in both $n$- and $p$-type PbS and PbSe was an order-of-magnitude smaller than in $p$-type PbTe.