Superconductivity in In-doped AgSnBiTe₃ with possible band inversion

Area of Science:

• Condensed Matter Physics
• Materials Science
• Solid State Chemistry

Background:

• Tin telluride (SnTe) based materials are known for their unique electronic properties, including band inversion.
• Chemical pressure is a method to tune material properties by substituting atoms, leading to lattice changes.
• Topological electronic states in materials are of interest for novel quantum phenomena.

Purpose of the Study:

• To investigate the effects of chemical pressure on the structural and electronic properties of SnTe.
• To explore new superconducting phases related to topological electronic states in SnTe-based systems.
• To examine the impact of indium (In) doping on superconductivity in Ag-Bi-Sn-Te compounds.

Main Methods:

• Synthesis of single-phase polycrystalline SnTe-based materials (Sn$_{1-2x}$(AgBi)$_x$Te) via partial substitution.
• Band structure calculations to confirm band inversion and topological electronic states.
• High-pressure synthesis of (AgSnBi)$_{(1-y)/3}$In$_y$Te samples.
• Measurement of electrical resistivity and specific heat to identify and confirm superconductivity.

Main Results:

• Partial substitution of Sn by Ag$_{0.5}$Bi$_{0.5}$ in SnTe resulted in lattice shrinkage (chemical pressure).
• Band calculations confirmed band inversion and preserved topological electronic states in Sn$_{1-2x}$(AgBi)$_x$Te.
• Superconductivity was observed in (AgSnBi)$_{(1-y)/3}$In$_y$Te for doping concentrations y = 0.2-0.5.
• Bulk superconductivity was confirmed for y = 0.4 with a transition temperature of 2.4 K.

Conclusions:

• The SnTe-based system with AgBi substitution maintains topological electronic properties.
• Indium doping in these materials can induce superconductivity.
• (AgSnBi)$_{(1-y)/3}$In$_y$Te and related phases are promising candidates for studying topological superconductivity.