First observation of fast oscillations on the high field magnetoresistance of (TMTSF)/sub 2/AsF/sub 6/.

Summary form only given. We present preliminary data on the low temperature magnetoresistance of (TMTSF)/sub 2/AsF/sub 6/, investigated in a high magnetic field of 37T at liquid helium temperature in the ambient pressure spin density wave state of the compound. Starting around 15T a single series of fast oscillations periodic in I/B is visible with a fundamental frequency very close to 200T. The AsF/sub 6/ salt is believed to have physical properties very similar to those of PF/sub 6/. However this frequency is substantially lower than the 230T measured in PF/sub 6/. More detailed experiments concerning the angular and temperature dependence of both oscillatory and background magnetoresistance are in progress.