G. Baskaran et E. Tosatti, POSSIBLE NEW LONG-RANGE ORDER IN SPIN-COMPENSATED FRACTIONAL QUANTUM HALL-EFFECT, Europhysics letters, 25(5), 1994, pp. 369-374
We discuss the even-denominator fractional quantized Hall effect using
Halperin's wave functions, and explain how this type of wave function
becomes almost a spin singlet, even though it is not an eigenstate of
the total spin operator. The SU(2) global spin rotational symmetry (v
alid in the absence of the spin-orbit interaction and Zeeman terms), i
s argued, based on this variational wave function, to break down to Z2
x U(1), indicating a <<nematic>> type of order. As a consequence of t
his symmetry breaking a Goldstone mode is predicted. Apart from this,
for both the even- and odd-denominator Halperin wave functions, the sp
ins are shown to have a chirality in the sense [S(0) . (S(z) x S(z'))]
not-equal 0.