Attospin and channel closings in high-order above-threshold ionization by bicircular laser fields

Abstract

In Phys. Rev. A 93, 051402(R) (2016), we proposed a method to introduce spin into attoscience with spin-polarized electrons produced by a bicircular laser field. In the present paper we further develop this method. We calculate focal-averaged photoelectron spectra and the corresponding spin asymmetry parameter by using the improved strong-field approximation. We show that the spin asymmetry of the rescattered electrons, which is time dependent on the attosecond timescale, can become especially large for particular peak laser intensities. The pertinent jumps in the spin asymmetry occur when the peak intensity changes so that certain above-threshold ionization channel-closing intensities corresponding to the different ionization continua of Xe become covered by the intensity distribution.