dHvA effect in f-electron systems

dHvA magnetization of U 3 P 4 and YbAs has been measured. The measurement for U 3 P 4 in the {1 1 0} plane shows a new branch. We have observed the dHvA effect in YbAs for the first time. The observed branches consist of ellipsoids of electron sheets. These sheets do not change its shape above and below T N .