de Haas–van Alphen Effect in LaOs4P12

We have succeeded in observing the de Haas–van Alphen effect in LaOs 4 P 12 which is a superconductor with the transition temperature T C =2.0 K and a reference compound for PrOs 4 P 12 . We have found the multiply-connected and almost spherical Fermi surfaces whose cyclotron effective masses are ranging 1.1–4.7 m 0 . The Fermi surface topology is close to that of PrOs 4 P 12 , indicating the localized nature of 4 f -electrons in PrOs 4 P 12 . From the comparison with LaOs 4 P 12 , the large mass enhancement in PrOs 4 P 12 has been clarified.