Apperently you were right about splitting the results in imaginary and real parts. This is my solution:
data= posteval(fem,'p','Solnum','all')
data2=posteval(fem,'imag(p)','Solnum', 'all')
data= posteval(fem,'p','Solnum','all')
data2=posteval(fem,'imag(p)','Solnum', 'all')