  Shubnikov-de Haas data is presented for a p-SiGe sample exhibiting strongly
insulating behaviour at nu = 3/2. In addition to the fixed points defining a
high field metal- insulator transition into this phase separate fixed points
can also be identified for the nu = 3 --> 2 and 2 --> 1 Integer quantum Hall
transitions. Another feature of the data, that the Hall resistivity approaches
zero in the insulating phase, indicates it is not a re-entrant Hall insulator.
The behaviour is explained in terms of the strong exchange interactions. At
integer filling factors these cause the 0 uparrow and 1 downarrow Landau levels
to cross and be well separated but at non-integer values of nu screening
reduces exchange effects and causes the levels to stick together. It is
suggested the insulating behaviour, and high field metal/insulator transition,
is a consequence of the strong exchange interactions.
