Successive destruction of charge density wave states by pressure in LaAgSb2

We comprehensively studied the magnetotransport properties of LaAgSb2 under high pressure up to 4 GPa, which showed unique successive charge density wave (CDW) transitions at TCDW1∼210 K and TCDW2∼190 K at ambient pressure. With the application of pressure, both TCDW1 and TCDW2 were suppressed and disappeared at the critical pressures of PCDW1=3.0–3.4 GPa and PCDW2=1.5–1.9 GPa, respectively. At PCDW1, the Hall conductivity showed a steplike increase, which is consistently understood by the emergence of a two-dimensional hollow Fermi surface at PCDW1. We also observed a significant negative magnetoresistance effect when the magnetic field and current were applied parallel to the c axis. The negative contribution was observed in the whole pressure region from 0 to 4 GPa. Shubnikov–de Haas (SdH) oscillation measurements under pressure directly showed the changes in the Fermi surface across the CDW phase boundaries. In PPCDW1, we observed a single frequency of ∼48 T with a cyclotron effective mass of 0.066m0, whose cross section in the reciprocal space corresponded to only 0.22% of the first Brillouin zone. Besides, we observed another oscillation component with frequency of ∼9.2 T, which is significantly enhanced in the limited pressure range of PCDW2