  A hole injected into a Mott insulator will gain an internal structure as
recently identified by exact numerics, which is characterized by a nontrivial
quantum number whose nature is of central importance in understanding the Mott
physics. In this work, we show that a spin texture associated with such an
internal degree of freedom can explicitly manifest after the spin degeneracy is
lifted by a \emph{weak} Rashba spin-orbit coupling (SOC). It is described by an
emergent angular momentum $J_{z}=\pm3/2$ as shown by both exact diagonalization
(ED) and variational Monte Carlo (VMC) calculations, which are in good
agreement with each other at a finite size. In particular, as the internal
structure such a spin texture is generally present in the hole composite even
at high excited energies, such that a corresponding texture in momentum space,
extending deep inside the Brillouin zone, can be directly probed by the
spin-polarized angle-resolved photoemission spectroscopy (ARPES). This is in
contrast to a Landau quasiparticle under the SOC, in which the spin texture
induced by SOC will not be protected once the excited energy is larger than the
weak SOC coupling strength, away from the Fermi energy. We point out that the
spin texture due to the SOC should be monotonically enhanced 1with reducing
spin-spin correlation length in the superconducting/pseudogap phase at finite
doping. A brief discussion of a recent experiment of the spin-polarized ARPES
will be made.
