Investigation of the β to β' Resistivity Anomaly in the Chalcogenide As₂Te₃

The chalcogenides are a family of layered compounds that exhibit interesting properties. As₂Te₃ is a chalcogenide that has α, β and β' polymorphic phases. Metallic β-As₂Te₃ is a metastable phase[1] that, below a temperature of ≈ 200K, undergoes a structural phase transition to β'-As₂Te₃. Within the region of this transition a strong signature can be detected in the resistivity beyond which it resumes a metallic behaviour[1]. We have employed a phenomenological fit on the resistivity of the β and β' phases of As₂Te₃ to better characterize the nature of this transition. Most notable is the occurrence of cross-transition invariance in the slope of the resistivity, a topic of considerable interest in other materials[2]. The direct strength of the β-As₂Te₃ to β'-As₂Te₃ transition as well as the width of the transition can be modelled using this approach. Drude-Lorentz fits to temperature-dependent infrared reflectivity data of the β and β' phases will be discussed to aid in the analysis of the resistivity and provide context on the mechanisms driving the electronic properties in the system.

[1] C. Morin et al. Inorganic Chemistry, 54(20):9936–9947, 2015.

[2] P Cha et al. Physical Review Research. DOI: 10.1103/PhysRevResearch.2.033434, (2020).