High-pressure characterization of Ag\(_3\)AuTe\(_2\): Implications for strain-induced band tuning

Recent band structure calculations have suggested the potential for band tuning in a chiral semiconductor, Ag\(_3\)AuTe\(_2\), to zero upon application of negative strain. In this study, we report on the synthesis of polycrystalline Ag\(_3\)AuTe\(_2\) and investigate its transport, optical properties, and pressure compatibility. Transport measurements reveal the semiconducting behavior of Ag\(_3\)AuTe\(_2\) with high resistivity and an activation energy \(E_a\) of 0.2 eV. The optical band gap determined by diffuse reflectance measurements is about three times wider than the experimental \(E_a\). Despite the difference, both experimental gaps fall within the range of predicted band gaps by our first-principles DFT calculations employing the PBE and mBJ methods. Furthermore, our DFT simulations predict a progressive narrowing of the band gap under compressive strain, with a full closure expected at a strain of -4% relative to the lattice parameter. To evaluate the feasibility of gap tunability at such substantial strain, the high-pressure behavior of Ag\(_3\)AuTe\(_2\) was investigated by \(in\) \(situ\) high-pressure X-ray diffraction up to 47 GPa. Mechanical compression beyond 4% resulted in a pressure-induced structural transformation, indicating the possibilities of substantial gap modulation under extreme compression conditions.