MAGNETIC PHASE-DIAGRAM FOR THE QUASI-2-DIMENSIONAL ORGANIC CONDUCTOR ALPHA-(BEDT-TTF)2RBHG(SCN)4

We have studied the magnetoresistance (MR) of the low-dimensional orga nic charge transfer salt alpha-(BEDT-TTF)2RbHg(SCN)4 at low temperatur es and at high dc magnetic fields. Electrical conduction occurs via bo th the quasi-two-dimensional closed hole orbit portion of the Fermi su rface (FS), as well as the quasi-one-dimensional open orbit FS. An ant iferromagnetic ordering transition occurs in this material below 10.5 K, which results in a density wave ground state. The consequences of t his ordering can be seen in the MR background, which measures the quas i-1D FS. This ordering can be broken with the application of magnetic fields in excess of 32 T for T < 4 K, or with applied pressures of abo ut 8 kbar.