Low Temperature Weak Anti-Localization Effect in the GeTe and SnTe Epitaxial Layers

Abstract

IV–VI semiconductors possess intriguing multifunctional characteristics, such as topological surface states, ferroelectricity at room temperature, and giant Rashba spin-splitting, giving them the potential for next-generation spintronic applications. In this work, we are presenting the epitaxially grown layers α-GeTe and SnTe, their structural and high field magnetotransport results. The crystal structure of α-GeTe preserves the rhombohedral symmetry (R3m) below T ≈ 720 K manifesting ferroelectric polarization, whereas SnTe holds the cubic symmetry (Fm-3m) above T ≈ 80 K. The results of the variable temperature in the range 4.3 ≤ T ≤ 300 K show a weakly dependent charge concentration, i.e., p(T) = 0.1 x 10²¹ cm^-3 for SnTe and p(T) = 0.7 x 10²¹ cm^-3  for α-GeTe layers. Likewise, the hole mobility µ_h(T) remains almost constant in the range 4.3 ≤ T ≤ 15 K and changes to a metallic-like behavior when T ≥ 15 K. Furthermore, the high field magnetoresistance ρ_xx(B) graphs of SnTe layers, measured between -13 ≤ B ≤ 13 T, demonstrate a prominent weak anti-localization effect below T = 3 K and when |B| ≤ 0.3 T. However, the weak anti-localization effect disappears at T = 4.2 K for both the α-GeTe and SnTe epitaxial layers. Similarly, the ρ_xx(B) graphs of α-GeTe show a small effect only at the lowest temperature measured T = 1.6 K. The calculated prefactor value α = -14, obtained by fitting the Δσ_xx(B) graphs with the Hikami–Larkin–Nagaoka model, indicates the bulk transport system in SnTe.