Electron localization in n-Pb1-xEuxTe

The electrical resistivity of Bi-doped Pb1-xEuxTe epitaxial layers with ele ctron concentration n approximate to 2 x 10(17) cm(-3) is studied as a func tion of temperature, magnetic field, and Eu content x. A metal-insulator tr ansition is observed for x close to 0.1. It is found that the large static dielectric constant of this ionic material epsilon approximate to 10(3) mod ifies the electron localization compared to standard doped semiconductor sy stems in two ways. First, the localization is not driven by ionized impurit y potentials but rather by short-range alloy scattering, which is particula rly efficient due to large offsets between the conduction bands of PbTe and EuTe. Second, only the singlet particle-hole channel of the disorder-modif ied electron-electron interaction is presumably contributing to electron lo calization. This leads to the absence of the corresponding magnetoconductan ce, and reduces the destructive effect of electron-electron scattering on p hase coherence. As a result, negative magnetoresistance brought about by in terference of self-crossing trajectories is observed up to temperatures as high as 100 K. [S0163-1829(99)09019-0].