  Spin effect on the pair production under circularly polarized fields are
investigated. Significantly different from what momentum spirals caused by two
counter-rotating fields with a time delay, we find for the first time that the
spirals can also be induced due to the particles spin effect even if in a
single field. We further examine the bichromatic combinational fields, the
inhomogeneous spiral structures can be observed in the momentum spectrum, in
particular, the spiral not only does exist in two cases of spin but also is
about two orders of magnitude amplifier than that in the single field.
Meanwhile, the spin asymmetry degree on the momentum distributions is
investigated and found that there exist the effect of spin flip with increasing
time delay between two fields. The spin asymmetry degree on the number density
can reach to $98\%$ in a certain of condition. These results indicate that the
signatures of created particles, especially the spiral structures are strongly
associated with the information of laser field as well as the created particle
spin, which can deepen the understanding of vacuum pair production.
