Evidence of new split FISDW transitions — transport properties

We present an angle dependent study of the quantum Hall effect in the field-induced spin-density-waves of the organic conductor (TMTSF)2ClO4. Hall resistance remains quantized until the the magnetic field makes more than 60 ° with the c* axis in the bʹc*-plane. Most of the successive first order transitions are split into two upon tilting the sample, of which the mechanism is different from that of magnetocalroric splitting. We discuss these results in terms of multiple order parameters and the interferences between two pairs of Fermi surfaces.*The work has been supported by the KOSEF under grant 96-0702-04-01-3 and 976-0200-007-2.