Significant change in the electronic behavior associated with structural distortions in monocrystalline SrAg4As2

Here, we report a combined study of transport and thermodynamic measurements on the layered pnictide material SrAg4As2. Upon cooling, a drop in electrical and Hall resistivity, a jump in heat capacity, and an increase in susceptibility and magnetoresistance are observed around 110 K. All suggest nonmagnetic phase transitions emerge at around 110 K, likely associated with structural distortions. In sharp contrast with the first-principles calculations based on the crystal structure at room temperature, quantum oscillations reveal small Fermi pockets with light effective masses, suggesting significant change in the Fermi surface topology caused by the low-temperature structural distortion. No superconductivity emerges in SrAg4As2 down to 2 K under pressures up to 2.13 GPa; instead, the low-temperature structural distortion moves up linearly to high temperature at a rate of ≈13 K/GPa above 0.89 GPa.