de Haas-van Alphen and Shubnikov-de Haas oscillations in RAgSb2 (R = Y, La-Nd, Sm)

de Haas-van Alphen and Shubnikov-de Haas oscillations have been used to study the Fermi surface of the simple tetragonal RAgSb2 series of compounds with R = Y, La-Nd, and Sm. The high quality of the flux-grown single crystals, coupled with very small extremal cross sections of Fermi surface, allow the observation of quantum oscillations at modest fields (H<30 kG) and high temperatures (up to 25 K in SmAgSb2). For H parallel to c, the effective masses, determined from the temperature dependence of the amplitudes, are quite small, typically between 0.07 and 0.5m(0). The topology of the Fermi surface was determined from the angular dependence of the frequencies for R = Y, La, and Sm. In SmAgSb2, antiferromagnetic ordering below 8.8 K is shown to dramatically alter the Fermi surface. For LaAgSb2 and CeAgSb2, the effect of applied hydrostatic pressure on the frequencies was also studied. Finally, the experimental data were compared to the Fermi surface calculated within the tight-binding linear muffin-tin orbital approximation. Overall, the calculated electronic structure was found to be consistent with the experimental data. [S0163-1829(99)09443-6].